With Sketch, for the year since your purchase, you receive all updates. Whether they are major or minor.
I get that it sounds similar to legacy licensing models, but it is not the same. I think it's a good blend of patronage/subscription and keeping-what-you-paid-for
With the old 1.0/2.0 paid upgrade model, you could go years before the next major version. You also got different tiers of upgrade pricing: upgrading to 3.0 from 1.0? Or from 2.0? Or are you buying 3.0 outright?
With something like Sketch, any time you pay $100, you get the latest and greatest for one year. If you want to take a break you're not financially punished for skipping updates
So I would say the Sketch model is quite a bit different