I wouldn't be at all surprised if Apple have an in-house solution, or if they've at least been wrestling and testing the idea for years.
No way they'll happily wait for somebody else to invent this technology, which everybody else can use, and then decide to use it.
True wireless charging (not charging on a mat) will really be a game changer and Apple recognise this, though in its very nature it would be very difficult and dangerous to pull off properly. It's not something to release in a rush.
My heart tells me Apple will be throwing the kitchen sink at the 2017 iPhone and blow everybody's minds, though my head tells me they'll continue with their 'S' upgrade cycle and continue to test/refine the iPhone 8 features for release next year. I hope my heart is right.