I have learned to use Samplitude Pro X3, which I picked up last year for a song. I'll switch to that if it looks like Sonar is about to keel over due to Windows or VST updates. Samplitude is a serious, heavy duty DAW with lots of features, and I didn't find it difficult to learn. It's not Sonar, but it will do the job...
I bet that keeping an off-the-grid computer frozen in time with Sonar on it will work for a while, but eventually the real world will force it's way through. Some new-fangled library for Kontakt will require the latest version of Kontakt, which will require the latest version of Windows to run stably, which in turn will require an update to Windows that will render Sonar unstable...or some combination thereof...