Maybe she will find a powerfull witch to turn her into an original vampire, after all she has the doppelganger blood.
For me Katherine to wake up will have a big shock, all she hid vulnerability will come to the fore. She will ask for protection and may fall in the clutches of Silas, all people she despised and trampled will want revenge. The only person I see is that Elijah would be moved if they return to find itself, will be another gulf between them, Elijah loves humanity of Katherine and do not want to turn her, but their love for me will overcome another battle and she will progress as a human being and then he will turn again, because he did not want to lose her.
If he turns her again I'm sure it will be a beautiful scene.
It's possible by taking the cure she can't be turned back which is a good writing move just to avoid the whole Klaus-will-hunt-her-again, also to force the character into a new path, this way they can leave her in the show with a purpose with actual character development.
As for the moves it's probably to take it out on Elena since she is the one that "cured her" by messing with Elena's and Damon's long-term relationship while Elena is off to college. Now this shouldn't be a black and white situation, like it doesn't work or not but it should half-work as Damon is definitely not over Katherine, he was on the hunt for a solution to open the tomb for 145 years, that doesn't go away that easily. It will be exciting anyway as Katherine's cunning and manipulative side was always something she was good at and also because she seemed to enjoy it.
I also believe she may be important to Silas which mean if she finds out that she is she we'll obviously take protection from him if she can figure out he's pretending to be Stefan.
I also think that Katherine will do anything she can do within her power to align herself with another vampire in effort to ultimately become immortal again. She is going to have such a hard time coping with being a human.
Since Damon is with Elena, I think that Katherine will try to seduce Stefan (Silas) and try to get somebody to turn her back into a vampire.
Yes but Elena will be off to college to some degree, Katherine will be able to 'bother' Elena by trying to spend time with Damon. I also think that if she will be important to Silas, Silas will likely pretend "Stefan" has fallen for her again so he can keep a close eye on her, likely to avoid somebody turning her by mistake (or at least trying to as I think she would die permanently due to the cure).