Switch is doing incredibly well. Nintendo is has no competition in Japan.
Sony really needs 7nm fabrication to get hopping so they can bring out a Mobile PS4. It is obvious that the Japanese market wants the ability to play their games on the go.
-Give them a Portable PS4
-Offer a 4G LTE or 5G model
-Add Calling & Texting to the PS4 OS (Would be great for VR regaurdless)
-Then bring it to the west, so I can move on from the Vita, and ditch my phone.
For what? 400USD???
Its not only point for what price, but something like that couldn't be made currently, beacuse you would need PS4 APU in 7nm for something like that, also battery would be much worse than Switch one in any case. Maybe in few years something like PS4 Portable could be possible, but currently is not.