Yes, the fast-paced gameplay is part of what makes 2D Mario more popular. But looking at the E3 trailer, none of that is present in this game. In fact, the core gameplay looks slower than the Galaxy games'.
I voted for option #3. Nintendo's previous attempts to make the 2D Mario audience buy 3D Mario (Adding 2D segments and linearizing the levels, streamlining the hub world, and even including a god damn DVD telling how to play the game.) have been met with no success; I doubt they'll eat this up either. I think most will just wait for the proper 2D Mario. (I do think it'll outperform the Galaxy games.)
Also, I... I just know the game will have awkward camera angles aplenty just to show off the amazing, magical 3D effects. I mean, the game's working title is Super Mario 3D, for Pete's sake.
But who knows. Maybe Nintendo will finally manage to make a traditional Super Mario Bros. game properly in 3D. (Though I can't understand why they're so hellbent on not just making a 2D Mario.)
