This system of app review and locked-down pay-wall systems makes commercial sense for now, but ultimately it is not scalable, doesn't provide quality and is too slow. Any system that goes against the grain of a major trend, progressing along a rapid trajectory, with rapid innovation... simply will not continue.
The point at which people realize that Google and Apple are hindering innovation, will be the point at which they will open-up, and hopefully become a free platform.
(although I'm hoping before that time, our Internet infrastructure and bandwidth will be ubiquitous enough that all phones will simply boot into a browser - it's inevitable at some near point in the future).