It will be messy, it will open oportunities to corruption, lobbying, crappy user experiences, unsafe apps, government abuse, nationalism, ... it is really a Pandora box.
But mess can be a fertile ground for competition and innovation when excessive regulation blocks it.
Today's app stores are just feature development labs for Apple & Google. There is no chance that anyone will be able to create a big business within any app store and keep Apple or Google out. Just ask big players as Steam, Facebook and Microsoft how they feel about Google's and Apple's stores.
If you're in the apps development business then you're just looking for golden opportunities for Apple/Google and being very badly payed for that.