Thomas_Mac wrote:
As far as I know, it wasn’t going to be demolished, just turned into a hockey rink

No, that's the whole point. The owners want to demolish the old buildings (for some reason they are not a historical or/and architectural landmark) and build a completely new hockey arena with several rinks. The museum's campaign to save the building was showing exact details about this project.
I was there on the day they closed and the guard (just a poor employee of the bad guys) didn't let me read the eviction note on the door, because it was a "private property"! The asphalt in front of the museum! Below are some photos from better days: the long building to the right of the entrance was part of the DH plant, but not part of the museum. In 2010 there were still plans (I've seen some design drawings too) for a new addition to the old buildings with workshop and I think with a new hangar for the "Arrow".



I used to bring my son there - what an opportunity for the young fellow! When he was 5 he knew more about airplanes and aviation, than when I was 15!
In 2008 I met Philip Gray in the museum - a former "Lancaster" pilot from No.186 squadron RAF, journalist and writer after the war. He signed his book "Ghost of Targets past" for me. This was a once in a lifetime opportunity!

Later I spoke to a veteran-volunteer, selling tickets at the entrance. He was a former guard in one of the German-POW camps in Alberta (No.132 in Medicine Hat I guess). He also told me stories one never forgets.
Now this is all gone.
I hope for the best and wish to myself to visit the new museum in this, not in my next life cycle (if there is any at all

).
Check e.g.
this article.