It's the "last" in the sense that it's the "last big-tent event version of Windows that was delineated by multi-year development & release milestones." No more big-tent releases like Windows 95. The new release model may also remove the idea of waiting a year or more for a Service Pack.
Basically, it looks like Windows release cadence will be more like Adobe Creative Cloud model: continuous incremental improvements separated by months
And will it end up with a subscription based model too? that's the issue here.
What I do expect is features and applications linked to be dependent and associated with a subscription.
Couple that with improved security to discourage and outright prevent applications from being loaded outside of approved channels, similar to what Apple is doing* with it's security settings now, and it may become easier to just pay monthly than do your own thing.
*Preferences, security, "allow apps downloaded from..."
So, just like Apple and Android phones, Macbooks, and I presume Chromebooks and Surface devices, OS updates will keep getting pushed to your device until your device can no longer function acceptably, and you'll be forced to upgrade the hardware.
This is the OS software industry's solution to the "problem" that the hardware became good enough for most people and new sales dropped.
