I think because of the timing in which these consoles came out, people are getting confused as to the "next-gen" of these systems. The platform holders could have done this at the beginning of this generation but it would have cost a lot to make the enhanced versions. PS4 and PS4K could have came out in 2013 but that PS4K version would have been hella expensive. They would still be playing the same games with the same developer tools but just more power. That's exactly what's happening here, but instead of releasing the enhanced version at the beginning of the generation, they waited (both Sony and Microsoft) so that the prices could go down. They are just enhanced versions, more power, but still the same thing.
Now will the "true next-gen" system come out and support only these enhanced versions as the baseline? Possibly, we don't know. It all depends on the technology that is out at the time and how much of an upgrade in computing power it is. So you can't say definitively if that is the case or not.