Refurbishment or not, it needs to (and undoubtedly will) stay open at least until the F&F coaster is open in a few years. I'd personally love if, after F&F is open, they were to go in and give Mummy a whole lot of love and overhaul it to give it a new lease on life, but realistically, I know it won't happen; I just can hope that whatever it inevitably gets replaced with is something wonderful. (And in a perfect world, we'd lose Mummy, one classic monster, to make way for our own version of EU's Monsters Land so we can celebrate all the monsters, but I digress.)