THe knights, will either retire, or get their swords remade.

I agree that one sword will probably break at one tme and be repaired. With soul fire? That would be cool indeed! But maybe they already are made with it, since they are link to God and angels.

The white council will get losses

Don't they always have losses since the begining of the war with the vampires?

I have another theory about Empty night: could it be that Harry and company will go beyond the Gate? After all, Empty night is Thomas expression. And we know he's working to keep the knowledge of the Gate and the Outsiders unknown. So he could be the guide to stop the bad guys at the source, even going to the extreme action of trying to lock them inside again.