If Karina isn't interested in continuing the work of her aunts, then there's Elisabeta-Maria, or Nicholas, if he's restored to line of succession. If Elisabeta-Maria isn't interested as well and Nicholas isn't restored, then it's all over after the deaths of Crown Princess Margareta and her sisters.
Personally, I have a hard time imagining any of the Hohenzollerns moving to Bucharest to cotinue the work of the Crown Princess, Prince Radu and Princess Maria. And even if they do, it wouldn't look very genuine, to me at least. Especially now that money from the Government may be on the cards.