Nurseries agree to a propagation license from the breeder and when they sell the vines they pass a fee (usually something like $1 a vine) back to the breeder.

Growers typically buy their vines from said nurseries, who try to insure virus free vines and produce in bulk and do grafting to rootstocks, etc.

A breeder would not usually be affected, because they would work with pollen. If they were working with this vine as a parent (unlikely) they would probably as a courtesy reach out to the original breeder, but they'd just be taking pollen from it, so the "EULA" would not apply.

There are thousands and thousands of grape varieties out there. Most consumers only ever taste a dozen. The genetic diversity bottleneck for grapes comes in general from consumers lack of education and their preferences for the same thing over and over again, usually with a fancy European sounding name so they can feel sophisticated while they drink their wine from a clone of a vine from 800 years ago that had to be sprayed with fungicides every 5 days to stop it from dying.