Although Sony abondoned us, the PSN service is still alive and there are still loads of multiplayer games which are still running fine, like Call Of Duty, Killzone, Need for speed and more. While using PSN with a hacked PSVita can sound dangerous, it's not. We have no record of bans other than people playing a game before it was released. (Even trophy hackers weren't banned from PSN although unofficial PSN leaderboard websites banned them. It's a wonder if Sony erased our existence of their minds). So you can play online and use your main account on your PSVita. But you may face some problems.