AranhaHunter basically replied above me, but Sony made sure it would be very difficult to go from a usermode exploit to "pirating vita games". I am not saying it is impossible, but I'm confident. It took years to get piracy on the PS3, and even the existing soutions are so impractical that the damage is mitigated. I believe Sony learned a lot from that, and the Vita is probably even more secure than the PS3.
As far as VHBL is concerned, there is no technical way it could ever be leveraged to play Vita games. For one, it would be too impractical so "real" hackers would start something else from scratch, and also, many people have tried to write iso loaders for the psp based on HBL, and haven't succeeded in the past 2 years, so I think we're quite safe on that end.
Finally, with modern consoles, I think the threat of piracy is also mitigated by the fact that hacked consoles lose access to the centralized "network" (in this case, the PSN). A Vita without online gaming functionality, and that has to stay at a "low" firmware in order to keep playing pirated games would not be very appealing to many players. This is what is happening on the PS3, and I would love to see numbers but I'm pretty sure the piracy numbers on the PS3 are fairly low.