The difference between the two is not that much at all. This idea some people seem to have on various forums about how PS4K games are going to blow away PS4 games.. it's just not going to happen. It's going to be the same games, with the same gameplay, with the same geometry, just slightly better textures, or a more stable framerate, or another tick higher on resolution.
A game like Shadow of Mordor launched on next gen consoles, and a short time later launched on previous gen consoles. The previous gen versions not only looked and ran worse, but they were missing the most fundamental and "next gen" gameplay element, the Nemesis system. With PS4K, this is not even something that is ever going to happen.
Not only is Sony mandating that it cannot happen, but why would devs even work on it? The PS4/Xbone userbase is like 50 million or so, isn't it? The PS4K userbase is 0. And it won't sell like the PS4 did. Why would they neuter their own games for a stop gap hardware version? A niche version.
The people who should have a problem with this in the future are actual PS4K owners. Because, like PC owners, their games will be held back by weaker hardware. Developers won't be able to use that extra PS4K power for anything actually meaningful. Again, according to rumors, this is mandated by Sony. Unless I have this wrong? Someone help me out if I am wrong there.
Bottom line, PS4 owners have nothing to worry about, unless their pride simply cannot stand not having the prettiest console version possible. However, what happens if, down the line, Sony makes the PS4K the de facto PS4 model? Then PS4 owners will have cause to worry. Until then it's a bunch of complaining about nothing important.