Google will eventually be the marketplace for the big "unmaterialised" software companies, with dozens developers, that no-one has ever heard of, except for the company name, and address. Such companies do not have a "personal g-account" with which thetactual developers publish to play store but rather a "company account".
I hope, and forsee, that by 2020 we will have 1 or 2 g-independent markets and that the final users will finally become aware of this.
The only reason why they haven't so far, is that the is no real difference between the apps proposed by G-Store and the independent ones.
Once the devs really start letting go of the G-Store dependancy and showcase their apps OUTSIDE, the users will follow.