Alternative to what? A law that says apple must allow alternative App Stores? I'm ok with that, and it might be useful to some people. I just don't think it will affect the market much.
The App Store "market" is not going to become a competitive market with a quick fix like that. Any solution that does make it a competitive market also tanks the business model. 30% to deliver an app is many times what a competitive rate would be. The competitive rate might be 0. We didn't have app stores before app stores.
Any kind of antitrust effort would need to start from the understanding that this is not a competitive market. Apple has all the power. A few app devs have the leverage to negotiate and everyone else is a price taker. You could "solve" it by regulating prices, enforcing a single price or otherwise limiting apple's choices directly. Or... you could leave it as is, which is (IMO) about the same as ruling that they must allow side loading or alternative app stores.
Similarly, it will be very hard to limit fb from making their app addictive, shrill or other such problems. Their incentives are very strongly tied to these.
In a weird way, I think Apple and Google proved it would have significant impact, at least enough for them to put sizable effort in stopping it from happening.
Otherwise Apple wouldn't be fighting tooth and nails to keep it at bay. Google also went pretty great length, through bundled contracts, backroom deals and scaremongering to dissuade partners and users from choosing the alternative means that are available.
From the "follow the money" perspective, it seems there's hope in that corner.
I mean, I agree that if Apple abandoned trying to control app delivery it would be a big deal. I just don't think a simple rule gets us there.