How about this: instead of dumbing down gear shifts to a press of a button like in Lost World, we start with an explorative, slow sonic game that controls much like Mario 64 and is evocative of how you first get into playing Sonic CD; then, on that base, we build levels around further options to shift gears upwards through multiple "jumps" that work like the triple jump, and each intiates a faster mode of running? They shouldn't of course all be consecutively more airy like it is with Mario because Sonic isn't really about that, but instead they'd be a similar premade set of different heighted jumps that you'd have to look for the correct terrain to be able to pull off without stumbling. Then in these modern times we can just stretch out the levels to start fiddling with velocity and slopes and possible routes to go rather than building routes you have to go.
Lately I've been pissed that there's basically no competition at all for 3D Mario. Devs just don't get the backflip platforming or the multiple jump thing.