Board Thread:General Discussion/@comment-11276487-20130728000308/@comment-4092092-20130813034137

unless the theory that  the eye of magnus is the stone for the snow tower (and it doesn't work if the stone leaves the tower), We can assume the Snow Tower still works.

Side note: my money is on Paarthurnax somehow being the Stone for the Snow Tower, which is partly why has to remain up there all the time. So as long as the Greybeards keep protecting him, the world is safe.