What I expect is some support for a $700 product that was bought within 3 years ago. And, that support should be AB and NK providing instructions for Win 10/BT issues. Both (Win 10/BT) of which were on the market well before the release of the 5700.
BTW, even Microsoft put out a patch for Win98 for that last major vulnerability that was found, so that argument doesn't carry water...
As a systems engineer, I understand the challenges of backwards compatibility and configuration management of multiple baselines, it isn't easy. That being said, every reputable company I know of, does it because consumers expect and demand that (especially with high dollar products).
As you can see from the responses above, this is a well know problem (even before the 5700 was released). The fact that they (both NK and AB) have just been silent on the issue (or pointing a finger at each other), speaks volumes. Give me your money, and once I have it, I'm done with you. Not the best business model unless you're the only game in town. Which BTW, does encourage competition....