The whole premise of this thread is flawed. OP, you are basing your opinion on the premise that Sony/MS NEED 4K in order to sell the concept of a PS5/Xbox Two. This false premise can be highlighted by looking at previous generations and they were sold on a lot more than just resolution. PS1: 3D graphics, Optical Media, Power; PS2: DVD player, Power; PS3: HD, Online store, Power; PS4: Immediacy, games, Power, PS4 Pro: 4K. Only PS4 Pro was sold on the sole premise of resolution increase. They were very open about this.
There was a lot more that went into the launch of every new console generation than just the resolution output. The increase in resolution is more a byproduct of the increase in processing power, and not the main sell of a console. Yes, it was the main draw of the mid-ten refreshes, but Sony & Microsoft aren't soooooo damn stupid to not have had their next consoles in planning already, even before Pro/X. I may be wrong on that point though... Yeah, maybe MS/Sony are just out of ideas, and there is NOTHING else that can be offered to attract consumers to the next gen, and both MS & Sony knowingly hobbled themselves by selling their mid-gen refresh consoles with the promise of 4K. I highly doubt it though, and a "move like Nintendo with the Wii & Switch" isn't something that just comes about all of a sudden, especially when running a multi-billion dollar corporation. You don't change course suddenly, it takes decades of nurturing a philosophy, so I would argue that "doing a Nintendo" is reserved almost solely for Nintendo within the console industry as it stands.
Sony and Microsoft's strategy is already plain for everyone to see. Again, the premise of the OP is very flawed on multiple levels.