Maybe there will end up being a single app store for both Android and Apple? As a small dev, you'd only have to deal with 1 upload, a single review process, one set of user reviews, etc.
The legislation would require Google/Apple to "step aside" and allow side-loading/alternative app stores, so yes?
Google and Apple would still be welcome to operate their own stores. A 3rd-party cross-platform store would compete with them, hence no monopoly.
Edit: I guess you read my comment to mean "Apple's app store would come to Android" or vice versa? That's a possibility. I'd prefer that to the current state of affairs where no direct competition is possible
I still end up with one more app store to deal with. Unless this 3rd party becomes a de-facto monopoly, there's no way you could afford to leave money on the table by not also dealing with Apple and Google.
It doesn't at all. You can continue to just publish your apps to the App Store and the Play Store, much as the vast majority of users will continue using those.
And the point of this monopoly busting legislation was to create a bigger monopoly?