> (If someone had told me 10 years ago, for example, that relational databases were soon to fall out of vogue for hierarchical/document databases or key-value stores, I would have said history seemed to be against them, but here we are.)
I promise you this is some sort of bias you have. Relational databases are still used way more frequently than NoSQL databases, probably to the tune of 1000-10000 times more.