It's not clear to me from the article what remedy they're proposing. Seems like it could be any of: * Drop the 30% fee * Drop the 30% fee for apps the compete directly with Apple apps. * Allow users to install other app stores.
I don't think they're proposing anything at this point but the obvious remedy would be to allow third party payment options.
Apples only (real) reason for forbidding sideloading is because then they could no longer force people to use their payments.
If developers were free to use 3rd party payment solutions, then Apple would probably be a lot more lenient towards side loading apps.
I believe that Apple generally wants to build what's best for their customers, except when money is on the line.