If not, then what would happen if all those of “noble” lineage were to die in medieval times? Then who would be considered a noble?
Not wanting to discourage further answers, but this question from a couple years ago is quite related to your own and has two answers, one from me, and one from u/steelcan909
https://www.reddit.com/r/AskHistorians/comments/i5qhi6/is_there_any_examples_in_the_middle/