We have lots of churches today that use vacated theaters, big box stores, and abandoned schools as buildings for worship.
For Christians, ultimately the building is just a building that is used to protect from the elements. Not to say that they didn’t do a restructuring and beautification program once they arrived, but that’s a different subject.
Any standing building no longer used has always been fair game. Even in the New Testament they met in upper rooms, people’s homes, and beside streams.
Same here.
The building is not the church. The people are the church.
In my town, the Orthodox Presbyterian Church (whatever that is) meets in a spare room of a Volunteer Fire Station. On Sundays the parking lot usually has a good crowd.