Nothing, its going to be a niche device for the remainder of its life. What it needs is a price drop to go with the slim model. $199.99 bundle with Borderlands 2 & Minecraft would've been the ideal bundle in my opinion, with a bundle free entry point of $169.99.
Who knows though, maybe SCEA's new leader will blow us all away and announce a nonport from them. SCEE & SCEJ are the only ones supporting it (from within Sony) and i'm sure its well reflected on sales. In a dream scenario the Third Party Relations studio thats porting Borderlands 2 will get FFT0 and get Enix and other Publishers on board.
I love the Vita but its no wonder its not doing nearly as well as the PSP once you compare most of the notable franchises that have appeared on the two.
What can Sony do from a software standpoint?
Patapon, Gravity Rush, Uncharted, Infamous, Gran Turismo, new exclusive Jak or Ratchet (or both), Syphon Filter, Twisted Metal, God of War, MotorStorm, Buzz, LocoRoco, Ape Escape, Resistance that doesnt suck, PaRappa the Rapper, Untold Legends, Socom, Warhawk.
Sony has yet to make a sequel to one of their Vita titles and I do think thats a problem. While obviously the PSP was out longer they managed numerous Patapons, God of Wars, LocoRocos, Jak & Daxters, Ratchet & Clanks, to go along with their notable first party franchises in Twisted Metal, Gran Turismo, Resistance, MotorStorm. Plus you add in third party franchises like not-dungeon crawling Silent Hills, X-Men Legends, Final Fantasy, Monster Hunter etc.
Sony themselves started a bad precedent for porting PSP games to the PS2 later its life.
Another part of it is Nintendo made a handheld that doesn't require AAA games. PS2 level graphics don't require huge dev teams or budgets. With its installment advantage and lower budget risk it will be hard for Sony to get publishers to swap.