I guess it would stink to have sunk funds into your building only to find that once the parent organization goes looie, it really wasn’t “yours.”
But fine, if that’s the game they want to play. I guess it would be wise to purchase it if reasonably possible, or look for a different place to meet. Some churches will host other ones at staggered hours, even cross-denominationally. I could easily see Baptist churches being sympathetic here.
When the PCA formed in 1973 they devised a system that the money sent up to the General Assembly was voluntary on the part of each congregation. The church building is also owned by the congregation.
The PCA figured it all out.