That Apple and Google would move the goalposts so often, and with such vigor, that it'd result in classes of programmers who do nothing BUT support the mobile platform for development.

It has been a nightmare of keeping up with the majors, just to be able to enter their carefully curated arena.

Nowadays when I build an App, I do Linux/Mac/Windows first, and the iOS/Android release, next. Fortunately there is a vast industry out there for toolkits and frameworks for solving The Platform Problem™ which has been shoved down our throats by a ravenous corporate culture which is hell-bent on ensuring that they own the computing platforms of the future.