If they make a 4k screen for this thing, it dang well better be a new sku. Why someone feels a 4k screen is necessary on a 12" screen, I'll never understand. But whatever. I'd have no problem with the resolution getting smaller for the sake of battery life.
As for the SP5 (and really Surface Pro as a whole going forward,) Microsoft needs to either start doing some serious work in making this more of a tablet, or just move on from it and put all their work into the Surface Book. If it can't have solid battery life, more applications/UI elements which provide a much friendlier tablet experience, and just overall better system stability, then what's the point. And seriously MS, enough with not shipping it with a keyboard already. Either drop the price of the devices by $100 across the board, or include it.
I get that there a lot of people who buy this because they NEED it for business applications, but like it or not this thing is compared to an iPad. If they have no desire to convert iPad users to Surface Pro users (and maybe they don't, I don't know,) then that's fine. But if they do, it still needs a lot of work as a tablet. It's a laptop with an optional keyboard.