The question is whether it's possible for a genuinely new competitor to arrive. Back in the earlier days, before Apple and Google were so entrenched, competitors weren't able to do it.

The modern smartphone became popular and dislodged the previous status quo because they were genuinely new form factors and interfaces. They didn't just steal the market away from Blackberry and Windows Phone, they invented a new one and starved out the previous.

And if a new platform were to arrive, they're so broad that it's entirely possible they wouldn't even compete on the App Store. When companies squeeze out and screw over others, and the market isn't able to signal that its not good, it's time for regulators to step in.