I don't think so. On the one hand all the previous releases would still be free, and the project you're shutting down to take commercial would surely get forked, if only out of spite. On the other there used to be many commercial unixes, and they're all dead now. Competing with free and equivalent doesn't work.
Yeah, but Red Hat is selling (support for) free software, not taking it proprietary. They're not competing with free linuxes, they're adding value in the form of support, which is a useful thing if you're in corporate shop and need to cover your ass. "Commercial" was the wrong word, I meant Solaris, Irix and friends.
The intention wouldn't be to release the package as is, but to first overhaul them to take out finicky parts, and to unify them under one design aesthetic. From the initiation of development, the source code would be locked down, and there would exist no free equivalent. Over time, the disparities would grow.