[exabrial]

This is anecdotal, and I've read cases of the opposite, so I know there are downvotes incoming.

I've yet to work on a system where NoSQL was I was like "thank goodness we didn't use a structured database!". Instead, every time it's been the HIPPO trying to defend the decision while everyone else just deals with it. NoSQL seems to be taking a giant loan... You're going to need to organize and parse your data at some point (or why would you keep the data?). Putting that decision into the future just makes it harder on everyone.

[zaarn]

Schemaless definitely has a few applications, usually systems related to tagging. Luckily you can easily integrate schemaless into your Postgres database with no performance downside all thanks to the magic of JSONB or FDW, depending on which way you swing.

The very few pure schemaless databases that continue to exist and where I'm convinced they will continue to exist for a long while are those that specialize a lot (ie, Redis, Elasticsearch, a lot of the Timeseries databases).