For me it is not just a question of whether Microsoft would deliver an update to Windows that would break Sonar it is the central role that Sonar has in my music making process. Sonar's central role means that it is dependent on and interacts in some way with pretty much everything else on my Music Computer.
I agree that the risk of of Sonar failing because of a Windows update is small I'm actually more worried about my UAD-1 and 24/96. The same is true about an update by IK Multimedia, Waves or another third party breaking Sonar, the risk is small. There is also the risk that an existing bug in Sonar will start to cause problems again the risk is small.
Then there is the uncertainty of change. My personal view is that supporting Sonar just became easier for third parties. Unfortunately the potential market just got smaller. While using what I already have may be safe adding new plugins now carries a risk. It may be small but it is there.
For me this led to the decision that I would invest in a new DAW and migrate to it. This has a cost and carries some risk. In some ways the risk is higher than that of sticking with Sonar. I suspect that the switch will require further change. It definitely requires some decisions about the plugins I have installed and those I want to use in the future.
There are a few plugins that have been discussed here that I may have to consider rebuying and one that I will definitely upgrade. There are some that I will learn to do without or replace with an alternative.
I concluded that buying a new DAW was right for me but that certainly does not make it right for everyone because sticking with Sonar until it actually breaks makes a lot of sense. I still have Kinetic, it still works. Sadly it does not support 64 bit Rewire or VST 3. It also has some idiosyncrasies that comes with being older software on a new platform.
That is a long way to say I expect Sonar to be a workable solution for some years. It's just no longer the right platform for me. And that will be true even if someone saves it.