yummay
As far as I can understand, all sonar version post-X3 era will eventually stop launching after cake's servers shutdown. (for authorization).
A surprisingly common misconception, which I suppose originates with those who insisted on calling the rolling updates a "subscription". Which it never was.
We are merely in the same boat as folks who stopped upgrading from earlier versions because they'd reached a point where the product already did everything they needed it to do. I stayed on 8.5 for years after its official retirement and didn't feel like I was missing anything because it did everything I needed it to do.
The problems will occur when you upgrade your computer and need to re-authorize. Dimension Pro, Rapture and Addictive Drums are going to be problems even if SONAR isn't. Perhaps other third-party components, too. Let's hope Gibson (or the bankruptcy court) does the right thing and sets aside a small budget for maintaining the servers. Or, even better (but less likely), allows CW to post unprotected versions for download.