This is a follow up to Caitlin Snow on The Flash.
There has been more then one Killer Frost in the comics. Snow is the most recent one, in fact she's a New 52 creation. The appearances in Animated TV shows and Movies and most Video Games have all been either Lincoln or Crystal. But one Lego DC Video Game uses Snow.
One theory floating around is that Cisco and Caitlin will only get their power after a Flashpoint like Timeline change. I kinda hope not, they can't change Flash's timeline without changing Arrow's too. And I don't want to have to wait till after Arrow is over. I'd prefer not to have a full Flashpoint adaptation, it's a good story but I hate the "Time Boom" idea.
On speculation of how new people can get Meta-human powers in the future. One idea I saw was that some people might be already effected by the Particle Accelerator explosion but their abilities need to be triggered. For Cailtin someone suggested it may happen as a result of getting blasted by Snart's Cold Gun.
The creators of the show have said however not all Superpower will come from that explosion.
What if one of the other three Killer Frosts is already out there, and somehow she infects Caitlin her condition? Snow isn't even the only one who's been a love interest for Ronnie. (in the Context of this show far Ronnie is a love interest for Caitlin, since she's the regular cast member).