What resolutions between 1080p and 4k can they use?

At this point I think it'd be a given that they'd use some sort of build in 4k upscaler 

My guess would be 1080p/60fps across the board with 4K upscaling. That to me seems the perfect compromise.

Atleast with the N3DS OR DSi, one could still play 99%  of games availiable at their maximum potential ( The DSi had a bunch of exclusive shovelware and while the N3DS was a modest upgrade it's not as if a whole lot of games were produced for it  ). Going from 900P-1080P to 4K on all games is a huge difference. I'm dissapointed Sony would even go this far considering they always supported all their consoles for a minmum of ten years.

Sony also had multiple versions of their handhelds albeit the difference are usually not as pronounced as the differences between Nintendo handheld upgrades.

What the hell are you talking about? DSi had exclusive games, N3DS has exclusive games, yet you act like Sony is worse. You don't know PS4K will have its own games, and it 100% will not, Sony won't do what Nintendo does. All games will work on all PS4s, the latest console model will just display/run them better.

Also LOL at that trophy count and claiming to be Mr Playstation.

Yep, that's the most likely scenario.

I expect the PS4K to be 1.5x faster, with the cpu being the most beef'd up part for 60fps. I don't see the gpu getting as big of an upgrade as the cpu seeing 1080p is already a standard on PS4, but it will probably be enough to get those few Ubi/DICE games running at 1080p, and of course a new upscaler to 4K.

OMG!! Everyone is dying to play all of these exclusive DSI games!!!!!

List of Nintendo DSi-exclusive game cards

So many N3DS exlcusives, I'm suffocating with all the games coming out for the N3DS ( http://www.gamefaqs.com/boards/997614-nintendo-3ds/72018252 )

4K anf 60fps is nothing compared to all of these great games, Lol.

Calm down son, I've probably played more games on playstation hardware at 17 then how many games you've played in your lifetime. 

I think we're on the same page here.

at 17 you played more games on PS than someone else in their lifetime? I find that humorous considering the trophy list :D

on the topic, seems like there's some substance to this whole thing but I remain 100% certain no 4k gaming is in the question. i would totally buy an upgraded unit with a beefier APU though (hello amd zen), it will be interesting to see what will turn out to be factual.

This is what SCE Vice President said back in 2015:

As there was a hand of favorite game title, no longer need to re-buy for every model change of the game machine, can continue to move even a hand-held game in the future of the gaming machine in the long span.
When the out performance enhanced version of "PS4.1" specific machine, what was 30fps in the current PS4 might be able to play at 60fps. In terms of "PS4.1" specific machine has been enhanced performance, it might be to be able to play in 4K native if corresponding to the HDMI 2.0. Also, if in response to the HDMI 2.0a, that the patch that is provided, it may be able to play the hand game with HDR enabled. Without re-buy the remake, such as HD Remastered at full price, in the "PS4.x corresponding patch" is provided at a low cost, path is provided, such as can be upgraded to the evolution version of the better image representation It might be so.

Selling patches is something I've been considering for a long time.