Yes, NOS/used high quality blanks still exist, and good vintage decks as well, but you're forgetting one thing: When it's being revived, artists want to put their album on tape. Yet they can't simply buy NOS blanks and do it with that. The tape needs to be spliced to the right length, duplicated using professional gear (which might or might not exist anymore), need to be put in shells, printed and sold. The amount of high quality tape pancakes (the rolls they load tape shells with) is dwindling fast, and new one isn't produced. Most what is still available, if at all, is speech-grade. Where vinyl can be pressed nowadays, because it's just PVC (but, most pressing plants are old and can't keep up with the demand much either), tape factories closed down or don't get high quality oxide because the manufacturers of that quit a long time ago. And you can't convince those chemical companies to create new tapes because the interest isn't as high as vinyl. I'm sorry to sound pessimistic, but I think a "true" revival like vinyl will not be seen with cassette.