One thing that I found most notable about the new Sonic trailer: those NOT-Death Egg Robots seem to have a black-and-yellow/silver colour scheme rather than the usual red-and-yellow that Eggman has. HMM...
I didn't spot that myself, but... given who you are refering too hasn't shown up in the main series, just the side games, and has a way complex (and contradictory I think) backstory, it does seem a little unlikely.
Geoffrey, I'm referring to the new Sonic 2017 trailer.
I dunno. Given that this game involves Classic Sonic in what looks to be a more present-time setting (rather than hopping between zones and times), bring back the time-space-hopping Doctor wouldn't be too farfeched of an idea.