True. But I do believe that many potential buyers already have a PS3 and thereform multi-platform titles such as Sly or LBP Karting might not be enough to incentivize such an expensive purchase, given the fact that, anyway, they will be available on PS3.
I have a ps3 (even if i have to admit i don't play it a lot lately) but there is so much to play on it and so much large scale games. I can totally see a game like that as a Vita game and totally ignore the ps3 version of it. I did that with Motorstorm. Never installed the ps3 version and i don't see the point in doing that.
I can definitely decide that a game like that is perfect for the Vita and is, in my case, a Vita title. It's not like the PS3 dramatically needs games you see..