Humans: Continue developing Jaina, Varian, and Anduin. This is very open ended. Next expansion, I imagine we might see Alleria and Turalyon, making things even more interesting. I think it's also long overdue that Danath Trollbane returned to Stromgarde and Arathi Highlands.
Regardless, Varian Wrynn should be the one to conquer the Sha of Pride, kill Garrosh Hellscream, and bring an end to the expansion for both factions. The humans in general need to be playing a massive role in this battle along with the Darkspear rebellion. And how poetic would it be if Varian Wrynn was the one to speak for peace between the Alliance and Horde in the end after the battle is over, just before tensions arise and Alliance and Darkspear Rebellion begin killing eachother?
Dwarves: If the latest scenario is, infact, dispelling all of the political tension (or even just most of it), it's about time we did some changes: Wildhammer and Dark Iron especially need to be more prominent in the Alliance, if they are infact part of the Alliance. And I don't just mean as NPCs -- though that's very important. I think that actual dark iron and wildhammer skins need to be available as options for dwarves. No special racials, just options to choose them. The ideal time to do this is during the model update.
More importantly, we need a new focus for the dwarves. Either have them find clues and hints leading to a way they might bring back Magni and start working towards that and/or have them begin talking about having a King of the dwarves once more, one that is not of any of the three clans -- but of Anvilmar, the ancient line. We have one -- Thargas Anvilmar -- that has not done anything in a while that deserves attention. He has the potential to be the lost King of the Dwarves, but it would need to be built up to.
Gnomes: Gnomes haven't done anything significant in a while, and it's high time that changed. The first massive thing that needs to be addressed -- GNOMES ARE NOT JUST MECHANICS AND ENGINEERS. They are extremely skilled pilots and marksmen, and it's time for that to start being seen. The majority of gyrocopter pilots should NOT be humans, night elves, or even dwarves, but GNOMES. If I had my way, the gnomes would be the captain/admiral of the flying airship in Pandaria as well, and certainly for the submarine in Vashj'ir (though it's a bit late for that now).
They need some more impressive technology as well. Chickens and zappers are fun and good for the comic relief (that is a gnomes job), but it's time for them to show their impressive talents as well. In addition to the above, we need to see far more mekgineers and tinkers in general showing off their impressive talents on the battlefields.
Gnomes also could use a more interesting leader. Right in front of (maybe even behind with this expansion) Lor'themar Theron, their faction leader is surely the least known of the faction leaders. However there's something interesting about the gnome racial leader -- he is elected. Think about the potential that arises from this. You could allow us, the players (gnomes only), the ability to vote for a new faction leader or allow Mekkatorque to continue his term. You could let US choose the direction of the gnomish race, and adjust accordingly. How deep this goes is up to you.
Frankly, if you did this, these are my suggestions: Kelsey Steelspark, the incredibly cunning and talented gnome rogue you meet in Tanaris, Gelbin Mekkatorque, the gnome we all know and love, and a brand new candidate, ideally a male mage or warlock, perhaps with a different approach than the others, possibly more. Even several more. During the period of an event or patch (pre-expansion event?), the gnomes of level 20 or higher (gnomes only, again) on all servers would cast votes on who they wanted. This could be incredibly deep and would potentially incite intense discussions and give gnomes a great deal of interest and pride for the first time in a long time.
And lastly, it's damn-well time for the gnomes to take back Gnomeregan and/or kill off Thermaplugg once and for all. If you want to keep the awful instance almost everyone hates, at least allow the gnomes to kill off Thermaplugg, and leave the terrible place and start thinking about building a new city.
And perhaps most importantly of all, it's time for gnomes to be more than just puns to bad jokes. I'm not asking for a deep amount of respect and pride be applied to gnomes -- comic relief is their specialty. But it's time for us to laugh at their antics and nature instead of making them the pun of every bad joke or insult. It's gotten so bad it's almost embarrassing to play one. That's not right.
I am aware this is a big list for gnomes, but it's damn well LONG overdue. Trolls have been in the spotlight (or at least playing very significant roles) for quite a few expansions, gnomes deserve to stand and be noticed, and for players to be proud of their race for the first time in literally years.
Night Elves: What made the night elves so significant and loved in Warcraft 3 (besides the fact that ... certain people were getting excited about an elven bikini warrior race) was their sheer savagery and ferocity. They made for such an interesting and diverse choice in World of Warcraft for the Alliance, yet as time passed (or really, did it even take any at all?) they quickly became tame tree-huggers. Just look at Ashenvale. Where did that ferocity go that once shook up even the mighty Grom Hellscream himself?
Instead of having night elves being passive, or throwing their lives away against the wall of the horde, or putting themselves in the paths of giant kodos, or even worse playing the role of cowards, how about they begin showing their brutal guerrilla tactics they were feared for in Warcraft 3's story, hiding in the shadows and striking quickly and deadly. How about bringing back the old Tyrande that wasn't needy and apologetic, but respected and strong-hearted, and most importantly, unforgiving and merciless to her enemies. I miss her. The new Tyrande has been, all around, awful, and generally non-existent.
Draenei: They have a massive amount of potential if the next expansion features the Burning Legion. They had damned well better play a massive role if they do. If it takes place on Argus, all the better. If Velen is a big part of spearheading the war effort against Kil'Jaedan, that would be perfect. In general they need to play a bigger, active role in the world and never have an entire expansion where they just sit on their thumbs and do nothing, let alone 3 in a row.
Although it might require a little effort, if the Exodar is repaired, how about updating it so it looks more that way? It doesn't have to have the inside totally completed, but it should look shipworthy if that is what it is.
I don't know what else to say until there is more information on the next expansion.
Worgen: This is a BIG one. Worgen, no, Gilnean lore dies the second you leave the starting zone. This is ridiculously bad. First of all, they need to have a major victory against the forsaken. Ideally, several, if there is still a war going on. If there is a truce between the Alliance and Horde, they need to have back the Ruins of Gilneas to rebuild their home, and have something more than a dead tree husk as a main city.
The other Greymanes should be more prominent as well. Hell, Genn himself should be, he has done literally nothing since the starting zone besides make an extremely vague and random comment on the sha in 5.1. How this is done is up to Blizzard, but they shouldn't continue to be ignored.
I think Arathi Basin should be updated as a leveling zone, include Worgen + Stromgarde vs forsaken + orc/troll content, with a triumphant return of Danath Trollbane, a retaking of the entirety of Stromgarde for the Alliance, and a big victory for the Alliance, where the worgen use their greatest strength against the Horde -- their immunity against the Val'kyr's sadistic efforts, ideally killing one of Sylvanas' last few Val'kyr and striking a blow deep enough that the Forsaken have to retreat back into Hillsbrad. (Ideally this part would happen during the Cataclysm timeline, where Garrosh is still Warchief, right after Hillsbrad for the Forsaken).
Pandaren: I won't mention Pandaren, except that I want them (and monks too, for that matter) in general to continue existing in some small way after Pandaria. Emphasis on small, however, and it doesn't have to be faction specific.
This is just my two cents and quite a few ideas on how to improve the Alliance. Most of all, we need more writers capable of passionately writing Alliance content to go along with the rich Horde content we get regardless. Please let me know what you feel about this, and feel free to add your own ideas as well if you have some you wanted to share.