Disclosure: Prior to joining IPVM I worked at integrators that sold Genetec, OnSSI and Exacq as a sales engineer, selling among many other things, SSA/SMAs. It became more challenging in the last 2-3 years, but we still had hundreds of thousands of dollars in recurring revenue from those SMAs.
The Windows update version comparison is an interesting one to me because a VMS is not an Operating System, its a application installed on a Windows or Linux operating system.
The more appropriate comparison is Microsoft Office Suite, and yes, Microsoft charges you when you want to update from Excel 2013 to 2016. Additionally, I couldn't even find a way to purchase Excel outright today, as it looks like it's only available through... software subscription (Office 365).
None of that is to say that SSA Models in video surveillance aren't out of favor in today's market. However, you named 3 of the most well known, successful VMS manufacturers in the world, so maybe it isn't hurting them as much as you might think? Quaint, adj., attractively unusual.