There are a few things Apple can do to help out consumers, satisfy regulators, and keep their business strong (ultimately, this is about them trying to keep control so they can make more money).
Keep iOS walled, but figure out how to do the third party store thing. Been doing it forever on computers, and it's time the phone/tablet world of Apple followed suit.
A couple more examples:
I see no problem with an expanded standard text message format (RCS). If Apple wants to still indicate "non-iPhone user" with green, fine. But it would be nice to send large video files and such via text to Android folks (who will likely never switch) without having to jump through hoops.
Adopt USB-C until wireless-only is market-ready (I doubt this will happen). Yes, lightning is better for smaller devices, but until they resolve all the idiosyncrasies of wireless charging (or, the tech world comes up with a standard that's better than what's current), USB-C should be the port on iDevices.
Open up Shared Photos to Android users. My wife and I just had a baby, and we post like crazy to a Shared Photos Album because we don't do social media. The only problem is that in order to share with Android users, we have to make a view-only public link, which we don't want to do. They need to figure this one out.
I know. Apple wants to keep all these "special things" to keep consumers, but there are just so many other myriad reasons to be in the Apple ecosystem, these walled-garden features are becoming much more frustrating when they don't evolve with the times.