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
"Except for the few things still missing" That's just it. It's still missing things. How are you going to start a mandatory rollout before it's even finished?