My prediction, is that through out the cataclysm expansion, we will see their relationship develop, becoming romantic next expansion. <-- Maybe I will just say that they will become involved at some point, marry, and live happily ever after with no timeline.
The Jaina/Thrall speculation has (finally!) been put to rest, but Jaina remains incredibly single.... and so does Varian.
If not each other, then who for each of them?