I'm not sure that the app economy wasn't a temporarily bubble. We've yet to see many apps reach the sustainable part.

Very few apps are successful charging the customer. A few games are successful selling in-app purchases, but even those almost never last. Social apps some times get popular but rarely find a way to monetize, they wind up selling themselves to larger businesses who use them as a loss-leader.

Compared to desktop and the web, the number of sustainable businesses on mobile apps is depressingly small.