>Are there any other theatres hidden in the theatre district that could possibly be restored other than the Times Square Theater and the Liberty?<
The Hudson (44th Street, East of Broadway) is used as a convention center for the Millenium Hotel, but is absolutely gorgeous. I think I read here that it has very limited wing space. But boy would I like to see a play in there again someday.
The Mark Hellinger (West 51st Street), currently the Times Square Church and often discussed here, could return to being a theatre in a heartbeat, and is a much needed large musical house. It's in positively superb condition.
Hammerstein's (Broadway and 54th Street) had a very brief career as a legit house and has spent most of its life as the Ed Sullivan Theatre, with its stained glass interior covered over by paint and panels. I've wondered what may happen to it when Letterman is finished, but CBS has owned it for so long, that I doubt they would ever relinquish it.
The Diamond Horseshoe (West 46th Street), an intimate nightclub/theatre in the basement of the Paramount Hotel, spent a bit of time in the 60s, 70s and early 80s as a Broadway theatre called the Century. It is apparently still there and not used.
The Edison (West 47th Street) is now used as the Supper Club. After Oh, Calcutta ended its long run there, it found trouble attracting tenants and was converted into a nightclub.
The Mayfair/De Mille/Embassy 345 is a boarded up former movie theatre on Seventh Avenue near 47th Street. It was once used as a vaudeville house, but I have no idea if it still has a stage, fly space, etc.
I think that's everything.
Begin at the beginning and go on till you come to the end: then stop.