While the Horde's next new race is pretty much a no-brainer- The Ogres, the alliance's situation is a bit diffrent. There are candidates aplenty, but there is no obvious choice. Here is what i think are the best possible options (I'm not counting naga, murlocs, Ethreal, arrakoa for several reasons, mainly because i think they are improbable at best)
My personal favorite
Alliance lacks a more primitive, rough around the edges kind of folk. All of it's races are fairly civilised (even the worgen, who under their beastly looks are very classy folk) and they certainly lack the Tauren-like primitivity of nomadic people living in tents and having a religion oriented towards the ancestors.
The Alliance also needs a race that is composed of powerfull and beastly individuals who do not have the fear to go into battle (they have only the worgen for that, the horde is pretty much composed of such races) and are in the same time (at least sometimes) pretty wise and in tune with nature.
Pandaren also look kinda like bears, durr, why do we need annother bear race durr.
The other possible option:
This also is a pretty obvious choice for the next alliance race. They are allready integrated into alliance society, but they are voiceless and leaderless, but that might change with the return of Alleria (should she return) The High elves are pretty much in tune with Alliance philosophy and lifestyle, so eing in the alliance will be natural to them
-Annother (third) elf race
-Pretty much Blood elves with blue eyes, alltouh this could be changed (new diffrent animations. Make the males look a bit less....gay...make the females look less anorexic, like they would break apart if they try their hand at wielding a mace)
The more obscure options:
Yep, that's right, half-orcs, a product of both orcs and humans, the half-orc is actually a possible race for both factions.
Altough Shunned by both factions, half-orcs are fiercely trying to prove themselves as capable aditions to the society they have chosen to live in.
In recent time, under garrosh's rule, they were actually banished from the horde, being deemed "impure", so they settled for joining the alliance (this is kind of make-up lore, but it is believeable)
This race can have as starting zone a part of the Swamp of Sorrows (probably phased, so it dosen't interfer as much as the normal zone of the swamp, alltough the settlement will be there even in the normal version) , wich is nice considering its close proximity to stormwind
This race is a half-half race, wich is something new for the Warcraft playable races.
A race in the alliance that is not so well accepted as the other races could make for a good plot.
An interesting culture mixing both human and orcish elements
Clearly a mish-mash of two existing races (could be considered as interesting and thus advantage tough)
Should there ever be a oceanic expansion, there should definetly be a northen system of islands harbouring tribes of Tuskarr.
This race is definetly very interesting to me, and i felt that they weren't that well represented in WoTLK (they only seemed to care about fishing, despite being attacked from all sides)
This race is a lot diffrent than anything the alliance has to offer, being tribal, peacefull and calm, they can definetly bring only nice stuff into the alliance.
Starting zone should be an island in the northen seas, and their district at stormwind will be in a part of Stormwin Harbor (naturally), a place not used very often, except for traveling with ships.
Wich one do you think is most interesting to you, or do you have any more suggestions, because mine are crap? (they could be)