Come to think of it, it does seem redundant to go back to the old timeline after another special as big as "Genesis". I mean, I don't think they could play it safe twice in a row without feeling stupid. But look on the bright side, Eggman never conquered Mobotropolis, King Acorn never lost his kind personality due to his old ally's schemes, the Eggman Empire is on thinner ice than before, , and the FF's are back, baby! Also, doesn't it seem lazy to just go back to the old timeline?
Reminder: The difference between the pre-247 and post-252 timelines is more like a paradox than a Genesis Wave. According to Ian Flynn and Aleah Baker, even though reality was altered heavily, this is the same planet that existed prior to Worlds Collide. Besides, Sonic's starting to like the change, can't you at least try and learn from him?