I'm convinced Classic Sonic isn't going anywhere. Sonic Mania and it's subsequent spinoffs/merch only did good things for the brand and a Classic Sonic comic is already confirmed so it's not like they're dropping him cold turkey. Maybe he'll take a few years off but he'll show up again eventually. What I am a little concerned about is SEGA being hesitant to greenlight anything that isn't a small-scale title that leverages old assets like Mania. They seem to see Classic Sonic as little else than nostalgic iconography they can exploit. Maybe all the poor feedback they've gotten over the years has convinced them that we wouldn't tolerate anything new, but all the feedback Mania got proves otherwise. The new stuff in the game got the most buzz and just about the only flaw that's commonly agreed on is that there wasn't enough of it.