If Sony provides the Hardware for console and Handheld plus their worldwide studios IPs and japanese 3rd party exclusives PLUS nintendios IPs in both Handheld and Console, they would become a monster never before seen in the gaming industry, i would feel bad for microsoft, but i doubt that they would go out since now they would only be competing against 1 and not 2, and more people would be able to afford all consoles.
that being said i doubt that will ever happen.