People for years said we would NEVER get a game like S3&K ever again and then we got Mania two decades later.
I wouldn't say it's impossible anon, it's just highly unlikely because there's so much going against it. You've got Sonic Team which is just straight up incompetent so trusting them to do even the simplest of tasks is a gamble. You've got the divided fanbase who can't decide where to take the series moving forward which leads to many people making their own attempts that often go nowhere because 3D fangames are complicated. Then you've got internet critics who use the Adventure titles as a punchline for the entire series, leading to resent towards the era in general. It's tough to really see the appeal of trying another Adventure game when so many people are against it from the get go.
I'm hoping that we eventually get something in the vein of Mania-style Adventure game in time. It could take over a decade and not even be made by Sonic Team but I'm willing to wait that long the same way classicfags were willing to wait so long for Mania.