It seems to me the collapsed front portion of the building was the original millhouse before the theatre was built behind and became the Tivoli. Here is what it looked like just before the brick on the streetfront collapsed:
The west wing had to come down after the brickwork crumbled.
While the Tivoli was a gem, the real loss happened years ago when the gorgeous Grand Opera came down. It stood next to the Tivoli right where Centrepoint strip mall is today. It was torn down in 1961.
Here is a photo of the Tivoli and the Grand side by side in 1929.
Photos source
http://cinematreasures.org