I like the direction this is going....
May I suggest (and I realize how hard it is to change original game design) you implement a challenge like.. something's chasing you (similar to Temple Run's monkey system when you hit the wall) or there's more and more down-hills which makes you go faster, and then there's gaping holes in the terrain you need to jump over or something....
Something that makes the user go "AGHH, dang it, I need to pay closer attention next time", where they get the feeling of a challenge and wish to do better next time
Not saying you aren't already thinking of it... but for it to become big it basically has to have a few key things like:
*Challenge (shouldn't be too hard considering the stuff you already have in the game itself)
*Fun (yet to be proved)
*Simple (seems like you got it so far)
*Looks n Sounds good (no sounds in the later prototype videos, but i'm assuming you're going to get good sounds with those crisp graphics)
Like I said I love where it's going, I just think needs a bit more than to it than "unlimited free-running"... there's tons of those out there already and most of them get boring, fast. Keep up the good work and try to keep us informed on the progress