So release the server code as OSS, data necessary to function & support community servers. Even in a crappy hard-to-support way, the community will usually figure out a way.

IMO, the move from community servers over to matchmaking & vendor only servers being the only viable option was a huge disservice to the long-levity of games. If I find the code around here, I could still get a Tremulous server running today for a few bucks, even if I haven't played that game for 20+ years.