I think some form of local theater would be quite welcome on Phuket. As a business model though - I wouldn't be optimistic.

As a community theater, it could probably be very successful. No need to necessarily rent a premises, as international schools or other places have appropriate settings that could probably be negotiated for.

I do think there are some people here who miss some of the cultural activities available in Bangkok, for example. I know my wife and I would and do enjoy the occasional things on offer here, when they are reasonably priced.

Of Chiang Mai - I don't know.