Here's a fantasy suggestion just to keep the lights on for existing users who don't want to switch.
What if a bunch of us existing users offered to "buy out" maintenance of all legacy Cakewalk products and pay the server rental fees (assuming that everything is kept on rented servers).
While there would be no future updates, keeping the servers up and loaded would at least guarantee that we'd have access to everything we bought (including online activattion codes) in case we needed to download it again.
If for some godawful reason a future Windows update harmed Sonar functionality, some of the money contributed might be used to hire a legacy Sonar developer to fix the problem (if possible).
I'd gladly contribute a reasonable amount of money (say $100) to this type of cause if it allowed me to continue to use my Sonar indefinitely.