The Pay Mini could also be available for the ones who use iPhone and have iOS on their phone. Also, the company has huge plans to invest in this app, and make it available on every future device as well. It will be much easier to implement it on the future devices, because all of them will be coming with the MST technology, which is crucial for this app.
There might be also a new accessory coming for the upcoming devices, to make easier usage of the application itself. There have been no rumors and leaks about this, so we cannot get any further details.
The release of the Samsung Pay for all of the devices, might happen in either mid or late 2018. Also, the Samsung Pay is the second most used mobile payment solution, siting right under Apple Pay. The Android Pay though is currently sitting at third place. If Samsung succeeds to make partnership with the competitors, they will definitely have guaranteed first place.