I think it was excusable in a game as dated now as Oblivion for there to be one single character body model for each gender, that varied in height a bit for each race, but I think the potential is there to make something much more rich in Skyrim. Imagine if you could tell by looking at an NPC if they had a high Strength (big muscles!!!), or if an NPC is brave or cowardly, have them cower and walk around head down a bit or stand tall with their shoulders wide and everything in between. There should also be an invisible (to the player) stat that affects the fat content of a given NPC. Why not have some Nords that are really strong but have a bit of a gut from all that mead? It could be an option in char gen for the player as well. Obviously it could have more depth and more options, I think stuff like this would make for much more interesting/deep differentiation between NPCs as opposed to more hairstyles or tattoos (not that those aren't fun or lore-friendly too).

It probably won't happen, it's too much work and involves modifying meshes and textures for equipment, etc. It could work using a procedural animation and deforming system for the meshes and NPCs. But I doubt Bethesda will use this kind of technology.