Schneizel ordering Suzaku to assassinate Charles? That's an interesting way for things to go. Supposedly he no longer considers him fit to rule...perhaps this is because of everything he's learned about Geass on his own and from Cornelia?
Being bitter over what it did to Euphemia, I could see Cornelia being willing to turn against Charles. As for Schneizel, perhaps he wasn't BSing when he said that he was afraid of Geass' power and the fact that he had no way of knowing if he had already been affected. Presuming the likely scenario that he has arabitions to rule, the possibility of having secret powers waiting to be used against him at any time can't be too reassuring.
He apparently doesn't realize that Charles can't be killed, though...it seems to me Suzaku can't succeed on his own, which is where Lelouch might come in handy.