I highly doubt it, since you can continue playing after the main quest, which would be difficult as a dragon, even if it's not permanent and you just get an ability that temporarily transforms you into a dragon, it would seem that this could very easily unbalance gameplay, And seems to conflict with the whole "We don't want to include levitation because it prevents some great design choices." thing, seeing as dragons can fly. Most likely, the reason Bethesda doesn't want to talk about the main quest because they want it to be a surprise is for the same reason one usually does not want to spoil a story before people experience it, because usuaully stories are more satisfying when you experience them without already knowing what's going to happen, as you want to see what will happen next so you'll keep following it to find out, and if he story involves some twists, it kind of defeats their purpose if you know what they're going to be before even experiencing them, as then you won't be surprised when they happen, and there could be a number of reasons why Bethesda might not want to let us know if werewolves or any other form of shapesifting is included, and not necessarily because it would spoil the main story. After all, Bethesda hasn't given us a clear picture of what Argonians look like either, and I doubt that's a plot twist.
I've started the similar topic some time ago and got mainly negative response. It was even confirmed by the poll that some people are ridiculously reluctant to any innovations.
I actually love innovations, so long as they positively impact the game, but I'm not sure if I'd enjoy becoming a dragon in this game, I'm not necessarily saying playing as a dragon could never work in a game, but it kind of requires that the game be built around it, just suddenly becoming a dragon in Skyrim could easily turn out to be either poorly implemented, horribly unbalanced, or both.