Ok, so there has been a lot of discussion about the character models and I've decided to do a quick breakdown of how long I think they would take to do.
So just to clarify my experience/expertise in this area. I have been working in the CG and VFX industry for approximately 5 years and have been creating my own 3D characters 3 years prior to this as a hobby and whilst studying computer animation at university (I live in the UK).
Concept -> Already done. The concept art for the character models done on release, were probably far greater quality than they could actually create due to the game engine restrictions at that time. Obviously, when recreating content, it is important to go back over the concepts to see where things can be improved, whilst still maintaining the original feel of the characters.
I'm not a concept artist, but I know people who could turn around several versions of this a week. Having a few concept artists working on this. You could have a solid design for all the new characters within 4-6 weeks. I think that is being generous as they are so close to the original concepts.
Modelling -> They already know their poly limits based on the new panda models. Sure the topology for the new characters are massively different. But I could probably create one of them in a couple of days and I'm actually not that fast at modelling. I know people who could get through 1 a day quite comfortably. After all they are still quite low poly characters and the topology design would be similar to the panda.
16 characters as originally planned. 2-3 days each (again being generous) 40-50 man days. Presuming they have 4 modellers. You could get these done in a couple of weeks.
UV/Texturing -> Completely new UV layout and asymmetric textures. 1 day for a UV layout at most. 1-2 weeks for the texture, depending on how many revisions need doing. 4 Texture artists = 4-8 weeks for textures.
Rigging/Skinning -> They should have a modular rigging system in place. Using the panda rig with a few alterations based on size and accessories. 1-2 days per rig. With an additional day or 2 for animator requests. 1-2 days for skinning as well. With 2 riggers they could get 1 character done a week each = 8 weeks for all characters.
Animation -> Knowing the quality of animation Blizzard puts out, this process probably took a long time. I can't think of how many stock cycles they need for each model off the top of my head. But probably close to the 50+ mark. Presuming that half of these only needed a few alterations and additions, like finger motion, facial motion and accessories. Whilst the other half needed a complete overhaul. Probably averaging at around 150-250 seconds of quality animation per character with an animator averaging 8 seconds of quality animation a week. I would say 25 weeks for 1 animator per character. So with for example, 16 animators they could have all the characters animated in 25 weeks.
FX -> I have seen some new fx, but not many and lets consider that as part of the new spell rather than part of the new models.
Breakdown for all new character models:
Concept: 4-6 weeks (3-4 artists)
Models: 2 weeks (4 artists)
UV/Textures: 4-8 weeks (4 artists)
Rigging/Skinning: 8 weeks (2 artists)
Animation: 25 weeks (16 artists)
Modelling can start during the concept phase. As can Rigging.
Texturing can start as soon as the model is done.
Animation can start as soon as the rig is done.
So with a decent iterative pipeline and with approximately 30 artists. The new models could be done in around 25-35 weeks.
For a new race/class, they would need all of the above for the male and female version of the character - With a lot longer time spent on concept design. A new starting zone designed, story that fits in with current lore, skill designed and balanced and much more.
I'm actually really looking forward to the new expansion! I just wanted to clarify a few things while people were throwing out numbers like 3 years and saying that's why we didn't get a new class/race. It didn't take them THAT long and if it did, they should invest in some more staff with the amount of money they make a month from subscriptions.