You mean get rid of Postgres and build bespoke database-esque systems for every use case?

If so, then no. It is not time for that.

Yeah, I'm struggling to come up with a really good time for that.

The best I got is if you are trying to do an old-school style video game asset/save game storage. But even then, the value in just using sqlite or even parquet is really high.

There's so many really good data formats that deciding on a new one at this point seems pretty silly. Particularly because what you sign up for when you make a new one is losing any and all tools that could be used to work with and diagnose that data.