I don't know what makes Samsung Pay different from Android Pay, but that's how Android Pay works on my Moto X. As long as the phone is unlocked I don't have to do anything at all besides put it on the terminal. Works great (except today at Office Max, but I think that was their fault - haven't had any issues elsewhere). The old WP app based solution was terribly inconvenient in comparison.
I assume that when/if a new, premium Microsoft phone comes out, this will be included. The market is maturing fast right now (though when I use my Moto X to pay, I still get questions and comments from cashiers who haven't seen it used before), and I think in 6 months it will be something that a new phone can't be without.