I'm not running the show, but I am working at a place that does this. One time fee for a perpetual license for the current major version, free support, and historically ~6 years of updates per version.
Users tend to be quite happy about it, and we're profitable enough to pay comfortable salaries and have...a lot...of runway.
Of course, this model is possible because there was never any outside investment.
I used to work somewhere that had a similar licensing model. I believe it was perpetual access to all updates (minor or major) released within 12mths of purchase, along with free support. Once your 12mths were up there were no further updates.
Last I heard, they were still successfully running a (small - 3 or 4 dev) business on this model.
Users tend to be quite happy about it, and we're profitable enough to pay comfortable salaries and have...a lot...of runway.
Of course, this model is possible because there was never any outside investment.