The Vita is comparable in power to the PS3, so those ports could look and play really well...but the PS4 is a lot more powerful...so Second Son would probably look so vastly inferior to its big brother version that portability won't matter...and people will likely tease the Vita for it.
I think the best thing to do is have a Infamous 1&2 collector thing come out a couple months before a Vita only version. They should make sure the Vita only one is better than 1&2 (duh), and it should focus more on the sandbox explore the city aspect than graphics.







