> Who is going to become the YouTube of AR/VR?

Hopefully nobody. Whatever infrastructure layer there will be powering AR, I hope it would be like using the Internet than an App Store.

If you look at current HMD manufacturers, everyone is constraining the operating system for a chance of becoming the AR App Store. If these companies really want AR to be adopted so bad, maybe lower the barrier to developing software for this medium? In that regard, yes, Apple is on the right track, but I do not think we will see any 'killer apps' on an iPhone. HMDs just have so much more potential.