Sony is missing a lot from this while they are trying to compete with Apple and Samsung which they cannot win.
They are missing a lot with this one where ASUS and Razer phone is getting a traction. This should have done by Sony and they are getting to catch up game again syndrome again. Mobile gaming is getting bigger and bigger.
I know I know they already tried this before but they really didn't tried that hard.
Take a look at the twin view docks. They could create an add on dock that will enable your Xperia phone to be able to play your Playstation 4 games on the go. I mean phone are essential in a daily lives of a person now. They can gather a niche then they can expand on it. All the power will be done thru the accessory and the phone will be your display that will also help with processing the power thru the games.
Maybe they are thinking of doing it because they saw the potential with how successful the Switch is.