This is what really, really pissed me off about the iPhone. When it launched and they gave it a desktop-class web browser engine and told people they were going all-in in PWAs (though I don't think the term existed at the time). Then v2 came out and they went sike! native apps, must be developed on our PCs, must be distributed by us, you must pay us to be allowed to develop, we take a cut of your income, and we're going to cripple the PWA engine to make universal, open apps all but unusable.
Dicks.
One thing I think people are expecting is that, say, all WhatsApp users will suddenly by free to chat with all iMessage users. All these laws will require is that the services publish APIs that third parties can use. My guess is we'll see more services like Beeper that let you hook into iMessage, WhatsApps, RCS, etc from a single interface. Maybe WhatsApp and iMessage will eventually federate with each other but I doubt it and the law doesn't require it.