From Tim, who posts in the comments section:
I'm intrigued by your "Attempt at Synthesis" ideas, particularly because parts of it have been tried before -- and worked. You mentioned that we should think of theatre as an "alliance" or a "guild." How about a "troupe?"
I was a member of an improv comedy troupe. We owned our own theatre space, which was indeed open to the public when shows weren't happening. We taught comedy defensive driving there. We opened the space to corporate offsites. People came in, learned about our shows, came back that night.Members of the troupe were available to speak at businesses. You could hire us to put on a show at your grandchild's birthday party. You met the artistic director in the lobby before the show. You could mingle with the troupe at the bar after the show. Audience members were loyal, came back a lot, often ended up auditioning for the troupe.
Best of all, we weren't stuck doing improv all the time. We could leverage the recognition we got from being well-known in the community to put on serious stage plays, make films, just about anything. (Not unlike seeing a movie starring Will "Saturday Night Live" Ferrell.)
We didn't try the economic model you mentioned -- but I've always thought more theatres should do more of the sort of outreach you discussed. It creates a community. It brings in audiences. It works.