Are you asking from a lore point of veiw? IF so then there'll be a long wait, about 5-10, if not more years til its able to be rebuilt (all lore wise that is). In-game wise, there is a bronze dragon in elven form, her name slips my mind at this point, near one of its bridges that allows players (not sure if both Horde AND Alliance can talk to said member of the bronze dragonflight) to change between "old" Theramore and the mostly destroyed version