This isn't a new idea (I posted something along these lines last year) but surely if the Vita is still struggling along in the west, why not license it to Microsoft, who can release their own version?
Put out the same hardware, call it Xbox Go or something similar, with an Xbox Live store button added on an MS-skinned interface, and Microsoft could do all its own work on first-party licenses. Both Sony and MS share revenue from hardware sales while developers would soon have a far bigger market to sell to, bingo!
Sure, this hasn't really happened since the 3DO days, but with threats including open source games hardware coming from Valve, cloud gaming and iOS, Microsoft could do with covering another base, while Sony could do with the revenue and a hand expanding the Vita's installed base.
Also, Microsoft lacks the advanced second-screen that Sony and Nintendo now have for their main devices. This helps them play catch-up in one go and is a lot better than MS's many screens concept which shows no sign of life. True, all this couldn't happen overnight, but as a concept, could happily tag along with the XboxNext launch.
Halo Portable would sell bucketloads, Forza Horizon players could take their games on the go, and other Microsoft products, especially older IP, would get a new lease of life in portable form. Any game just needs a "compatible with MS Xbox Go and PS Vita" sticker to avoid market confusion and gamers get the best of both worlds in one format.
With such a deal, Microsoft and Sony can but up a block on Nintendo's dominance, while covering off these new threats. Yep, its a mad idea, and unlikely to ever be discussed by the folks at the top of either company, but I think it makes sense, especially the longer the Vita continues to bump along.