I don't think Apple will shut it down, but many users will probably not want to use it -- due to the bandwidth requirements. A 4K monitor uses a lot of data, and Apple is supposedly using Apple Silicon enhancements in Sonoma to improve high-speed performance. My guess is that one of the reasons for Apple supporting only one monitor is that multi-monitor use can melt down into a laggy mess. That's not an experience Apple wants to be publicized.