Seeing how they're keeping her until sept. 2013, I think they're just warming their fans up for her before they announce their decision. But anyone who knows anything about symphonic metal (repeating myself here) knows Floor, so I think that is not necessary.
On the other hand, seeing how they've completely misfired choosing their previous singer, even though it took them awhile (it was a sort of a "we totally trust her she'll be able to nail old songs based on a few rehearsals, and she has a kid already and might want more and she's never toured but she'll totally be able to handle world tour after world tour"-deal), maybe it would be good for them to first do a full tour with Floor to see if they want to stick with her for the rest of their career. But if they decide they don't want her... I seriously have no idea who wouldn't be underwhelming after having Floor.