Speaking of Samsung Pay, I can actually see it being far more used than any other solely NFC based solution in the US. Samsung has to make deals with banks just like Apple, so they're likely going to send tokenized magstripe data that isn't going to make the terminal try to force a card insertion. That alone will make it usable in far more places than Apple/Android Pay.
The downside of course is that it keeps magstripe technology alive. But that might very well be necessary simply because there is seemingly such a strong undercurrent of resentment against the major card brands that anything that makes card use easier for consumers that requires investment on the part of retailers is basically a no-go. In fact, I feel like being EMV and magstripe only (even if the hardware has NFC capability) is pretty attractive to them because their customers might be more inclined to use some other alternative, possibly one that the retailer controls.
We'll see how many retailers who become EMV compliant by October also turn on NFC, but my guess is that NFC at a lot of places will come much later if at all.