Not only has Yuji Naka, former head of Sonic Team, voiced his concern (like almost everyone else) of Sonic's movie design (and feeling partially responsible for some reason - It's not your fault, Yuji!) but apparently he was also asked to be cast into the movie however it looks like something fell through.
そう言えば映画にエキストラ出演させて欲しいとお願いしていたのですが、忘れられたようですね。かなり前なので私も忘れていました。ハリウッド映画に出演したかったんですけどね。— Yuji Naka / 中 裕司 (@nakayuji) May 2, 2019
Translated into English roughly with Microsoft:
Hollywood Sonic's design is unpopular and I was reminded by chance, the CG of this movie is like making, the predecessor of the Marza, Sega's Visual entertainment department because I made I felt sorry for my responsibility. https://www.marza.com/news/article/764/
Speaking of which, I was asked to make an extra cast in the movie, but it seems to have been forgotten. Because it was long ago, I also forgot. I wanted to appear in a Hollywood movie.
As we already saw earlier, it looks like we can expect more people that were involved with Sonic in the past to be in the movie in some way or another.