I am on OnePlus and I miss many things about Windows Phone daily from camera, wireless charging, automatic text reading and Cortana but it would really take an awesome hardware (which of course they have nothing for this year) to win me back. I agree notification is far superior to Windows Phone and one thing they really need to improve, I never have issue with Nokia Map and in someway I rather prefer it so to me it's a toss up there, as far as app I know I will miss a few if I go back to Windows Phone mostly the boardgame I play with my brother-in-law but I can always just pick up a tablet for that.
I think deal with Verizons is probably will be what finally kill Windows Phone in the US. While At&t is not always great but they were at least pretend to want to support Windows Phone, at least at one store I go to they never shy away from selling Windows Phone. Having your flagship phones both ties to one carrier that doesn't want to sell it in the first place seems like a sure fire way to sink your marketshare even lower.