Sony is not dumb enough to attempt another portable.
At least, I hope not.
According to the channels I have been watching and with respect to Sony's own pre-Switch patents, I am gonna throw my hat in the ring and say we get 2 PS5s:
A standard PS5 with full backwards compatibility to all existing Sony console games.
A PS5 lite with full PSP, PS4 and PS5 support. And Vita support. One assumes that PSOne support and possibly PS2 support will be considered as well.
The idea of playing KH3, Call of Duty, Marvel Vs Capcom. Horizon Zero Dawn, Spiderman and God of War in portable is far from dumb.
The support from this rumor comes from many sources including Japanese outlets, insiders, AMD's confirmation that Navi is scalable architecture, and of course Sony's own patents.
The final source is also Sony and goes back to their comment about the Switch and what it takes to regain strong competitiveness in Japan against Nintendo.