Bamco actually localize 3 games for Vita this year (Tales of Hearts R, SAO and One Piece). Also I heard that despite the low hardware sale, Vita software attach rate is actually quite high.
There's still hope.
Unlike Digimon though, those three tittles are related to things that have gotten a huge following recently. The tales series have been brought for the most part rencently, excluding spin-offs. Sword Art Online was a one hit wonder series, it got a huge cult following similar to Attack of the Titan (perhaps Bandai might also localize the 3DS game later on, who knows). As for One Piece, well, it's friggin One Piece, the number one anime and manga in Japan, it's also really popular in Europe (dunno about the USA), and that game will be released for several platforms, not just the vita (so, if the Vita version doesn't sell a lot, they have the other versions to cover that hole).
Digimon however, has been badly managed in the west. The english dubs are crap, like seriously, they are bad even compared to the old ones, and lastly, they don't really advertize it, something that they used to do a lot back in the 90's and early 2000's.