In a few weeks, 1% of creators already using YouTube Studio will no longer see the ‘back to Classic’ button – you’ll be notified 1st & can still access Classic features you need! This won’t apply to everyone else until early next year. More info → https://yt.be/help/a7mG
Furthermore, why get rid of the Classic anyway? If people are using it more than the current, that should tell you something right? Every person I've talked to about the new Studio says it's a waste and Classic is far better. DONT FIX THINGS THAT DONT NEED FIXING!!! LISTEN TO US