If they can work out a partnership, sure why not.
Especially if they could work with Nintendo and score some of the component deals on the next handheld (LCD screen, cameras, battery). Thats good for Sony, good for Nintendo.
It's not really "third party" in a traditional sense though ... there is no alternative here, it's Nintendo or make silly/cheap smartphone games.
Sony did make some good money off the PSP and some of their franchises did sell well on the PSP ... Gran Turismo sold 4.6 million, God of Wars 3.5+ million ... that's not charity money.
Sony's IP, especially the Western ones, would fill out Nintendo's handheld portfolio nicely too since Nintendo lacks in Western IPs on the handheld side badly. Things like God Of War, Uncharted, MLB, Last Of Us, Gran Turismo, Killzone definitely would bring a different (and welcome IMO) dynamic to Nintendo.
I think if Sony threw more support behind Nintendo other third parties like EA and Square-Enix and Konami would also follow suit. Perhaps Street Fighter V could also be allowed on the HDS (after the PS4 version of course). Works for me.
