It’s still there, although there’s a loophole of course.

4.5.4:

Push Notifications should not be used for promotions or direct marketing purposes unless customers have explicitly opted in to receive them via consent language displayed in your app’s UI, and you provide a method in your app for a user to opt out from receiving such messages.

The “explicit opt-in” could easily be language hidden in a massive ToS that nobody reads. So I guess I wish Apple would do away with that entirely and start enforcing it.

Since the question is specifically about what Apple could make developers do, I’ll say this: enforce the App Store guideline rule about not using push notifications for advertising.

I very rarely enable push notifications on apps anymore because so many use them for spammy advertisements. This makes apps less useful than they could be if notifications were used responsibly.