The problem with this thread is that everyone is thinking logically and rationally
I've been involved in some licensing deals at Gibson and while some are painless, some are a nightmare. Regarding the specific plug-ins, we've been over the VC-64 multiple times. I LOVE that plug-in. I have nothing that can do what it does (although if the Blue Tubes FX could run in parallel...), and I fear the day when Windows or SONAR or something changes to the point where I can't use it any more. Cakewalk would LOVE to acquire the rights, but can't find where to obtain them.
Another issue is support...suppose you have a problem with R-Mix and SONAR Titanium Mega Plus Turbo Ultra when it comes out in 2019. Cakewalk doesn't know the code, and I don't think Roland would want to support a product that no longer exists. As to Lexicon...I think Harman still owns them, but I'm not sure of the Pantheon's heritage.
Realistically, probably the best we could hope for is the "Bapu Solution" of having some kind of installer that prompts you to install from previous versions of software you own. I don't think Cakewalk could legally offer an installer containing the code they no longer license, but maybe they could offer an installer to install the code you've licensed. Maybe. Possibly. Who knows? I don't...but I
do know lawyers charge by the hour