You’d think Sonic Team is the obvious choice for Sonic 5 but, the truth is, they’re no longer the best developer for the job, in my mind. At least not for a new 2D Sonic game. It isn’t that the quality of Sonic Team's recent output has been bad. In fact, 3D Sonic has never been so good, with Sonic Generations and Sonic Lost World both offering slick, exciting and enjoyable 3D experiences. But Sonic 5 should, in my opinion, be a 2D-only game. And I've yet to see a 2D Sonic from post-Naka-era Sonic Team that controls like it should. Yep, the old problem.
The pinball-bouncing, slope-rolling, ramp-hitting Sonic you can play on a Mega Drive/Genesis is all about inertia. Sonic Lost World does have 2D levels and they look incredible, but still are simply not what 2D Sonic should feel like. Sonic Team's top priority no longer appears to be ensuring the core process of moving the character is enjoyable in itself and there's always something wrong, whether it's the jump height, acceleration speed or behaviour on slopes. So who could do it 'right'?
Odds of happening? The most logically strong. Like if Spock had been working out.