(This is my opinion and most of the stuff here could be very wrong, take it with a grain of salt, just wanted to put my thoughts down in text)
Obviously, anyone would think it's a very big undertaking. But to be honest, it's probably the biggest ever that they've done. Far, far harder to craft than even a few raids. It means that we'll have to wait a good while and also that there's more reason to be excited for them... well, and lastly, that the controversy has potential to be really big. Which ain't good.
It's not just about a simple aesthetic facelift. Trust me, if that was the case, they would have arrived far earlier. That's easy enough. I'll try and list all of the changes I think they are going to make:
#1.) The polygons are going to be increased by quite a bit, at least to the standard that they are putting out now with the new race NPCs. That's a given, I think.
#2.) I think they are going to tweak our animations a bit and give us some new ones. It won't be that drastic though, because Blizzard has said that there's a fine line between changing for the good or for worse. They also said (in a tweet, I believe) that people are really attached to the way their character moves, so not too much change. Undead are probably still going to make a low seeping motion with a 2-hander, for example.
However, I think they're going to be adding more than 1 animation for a special. I think they'll want to give 2 to 3 in total that randomize each time you swing your weapon (when pressing a special attack, e.g. Mortal Strike), just like white attacks. I also think they'll start giving some new unique animations to some abilities (where there's only 1 animation all the time, like Slam) like Eviscerate, for example.
#3.) The spells. I think they are going to update spells soon after the characters are re-done. It's going to look awkward casting a spell likely developed in 2002-2003 before WoW retail even shipped (There's still spells like that out there) on your new toon. It won't happen right away but I can see it happening at an increased pace, possibly a bulk being done for the upcoming expansion.
Maybe they are crafting the new character models to suit what they want out of the upcoming spell visual upgrades. Maybe they want the character to catch on fire at certain parts of the body when he's hit by a Fire spell, possibly leave burns until combat ends, who knows? That would be pretty damn cool.
#4.) Gear. Of course, the gear we are getting has been more and more visually impressive since the start of the game. The art and quality of it has definitely improved. Look at Tier 1 Might set vs. the Challenge Mode set, for example. Drastic improvement. However... it's still severely limited in terms of creativity. We have about 4 base boot models. Here they are (aside from the ones that look like socks):
And that's all there is to it. Same with glove models, etc. They could do so much more to them. Take a look at the new Mar'li model on MMO-champion or WoWhead. They really could be more creative, but probably there's some limitation with the current character models.
Capes. They've been awful since forever. I don't think people can really say they haven't, almost no one actually displays them, only a very small percentage. I think Blizzard is sorely needed to improve this part of gear and make them more like the Lich King or Sylvanas' cloak. Possibly create some real tattered looking capes as well.
- They might upgrade the polygon count on our racial mounts go along with the updates. Possible that the Gryphons and Wyverns in 5.1 could be a sneak peek.
- What would be really cool, is that they give everyone a free race change.
That's it. My thoughts. Comment away.