last thing i read was in FM:updates (in the crusader wolf clan section "all that is known about her fate is she has been striped of her surnames". anything new since then?

Well, shes obviously not a warrior, and wouldn't stand a chance of becoming one, so aside from being with Vlad she'd effectively have no real power in Clan Wolf. She shared a mutual feeling of respect and attraction with Vlad that much was known. Since I doubt I'm far from the truth if I were to guess Katherine, even after losing all power and being given to Vlad would give up her aspirations of ruling the entire IS. And we know Vlad has never given up the crusader dream and they're both just delusional to think they can manage to take over the entire known universe some how. So they're probably working on some nefarious scheme while talking about how much they hate Phelan Kell. Thats just my best guess with the information I've read.