4K gaming in a beefed up PS4 is out of question. If the rumor is true I'm sure Sony will keep the price at $400 and with that they can just put a more powerful APU (2.5-3 TFLOPS? Plus a decent CPU this time) and maybe some faster RAM good enough for 1080p60fps (mostly) and 4K videos.

Technically it's doable because of the PC like architecture, with better and cheaper components coming out nearly every day. And from a consumer point of view that's what many people are doing already with mobile devices. They are already used to the idea of upgrading every one or two years. 

What it may happen is that the PS4 may have (or may not, since nothing is official) one or two upgrades, with all new PS4 games required to run in the first (less powerful) PS4. Then if there is the need to make a clear cut Sony may introduce the PS5, PS4 backward compatible but with its games not designed to run in the PS4. Unless they are specifically ported, tested and ceritified for it.

With MS moving toward PC (actually Windows 10) gaming a similar strategy IMO would just make sense.

multi-console owner and pc and definitely won't buy a PS4k.

Probably not; PS4's achilles heel for me is the lack of quality exclusive titles, and a 4K version of that doesn't really incentivize me much.

I believe that version will suffer too. Developers still need to test and make sure the game runs on the new system with different hardware specs. Yet the sales expectations are exactly the same, hence that extra cost comes out of the overall budget. Thus I expect less specific optimizations overall, even though they'll spend the lion share of their time on the current system. It's more work for developers for no extra gain.
In the best case scenario games will run exactly the same on the ps4.5 (if you can ignore the extra resources) so developers can fully concentrate on the current version. Which means only a few first party exclusives will actually use the extra power.

If I were to get a PS4, I would get the original version as it would be cheaper and my TV doesn't even have 4K

I don't have one, so if that was an option, I would take it if I decided to buy one down the line.

nah no point, my current PS4 is fine.

no thanks

My ISP only gives me 25 Mbps so no 4K streaming, therefore no 4K TV, therefore no PS4.5 for a while.

Not really. I'm satisfacted with my current PlayStation 4 and wouldn't drop an extra $400 for it. Maybe in the distant future when the new model is cheap ($200), but not in the near future, that's for sure.