I do not think they will be replaced by the 50th. I do think they current fleet will still be around for the 50th. I am unconvinced either way as to if the 60th WDW anniversary will still feature Monorails. But for now they are refurbishing the trains one by one. Orange and to a lesser extent, blue, are in good shape right now. Gold is currently under the knife but Orange is already showing signs of grime building back up. Sadly it seems impossible for them to keep them clean. What changed? They use to keep them clean?