It's hard to say. If anything I might lean towards him dropping a little but I can't imagine him ever falling as low as out of top 15. Absolutely not a top 5 character though.
Well, he does have kill throws, but they're weaker than all of the other kill throws, lol. His damage output is really good, and honestly so are his combo confirms. Like, Sonic is still very good. He also has some of if not the best mobility, evasive tactics (you guys take Spring for granted) and a lot of tools that help keep him slippery and break neutral. The problem is though he relies on the bait & punish as said as well as basically avoiding neutral... Plus outside of his damage combos he relies on rare 50/50 or just hard reads for his kills, can't safely pressure shield, lacks a good neutral game, and requires a lot of time to yield results.
Whether people want to admit it or not, there's a reason why you only see Sonic mains and no one with a pocket Sonic. He doesn't have any match-ups that he dominantly takes in the top tier that another top tier can't cover better, plus he's one of the most technical characters in the game with his multitude of mix-ups and movement options that demand precision and practice... You can't just run around and spin at a top level without knowing every little quirk to it.
Sonic's weird.