I don't think they'll be putting it on phone screens, unless it's some sort of new compound. Sapphire watch crystals is a pretty premium thing, and even with a big plant like they have, I don't think it would be close enough to put on millions of iPhones. If you go look at any $700+ watch, it's likely to have a sapphire crystal. Everybody has been screaming "new iPhone screen material!", but I don't think that's the case.
I think we will be seeing it on larger home buttons, iWatches, and cameras. My jaw will drop to the floor if they end up replacing the gorilla glass completely with sapphire.