What does the ultimate database look like? Maybe the ultimate database of the future going to be a many-headed hydra that will attempt to solve all problems? Maybe marketing teams are going to be at the heart of its success? Perhaps it will grow tentacles and become violent toward its creator?
Unless you're a contributor to the software, your probably limited to understanding the value propositions and a subset of features. Maybe your an expert. Probably not. This corner is usually dark. A database has historically been a black box. You pick one that seems like the best fit and trust it.
Maybe the database of the future should just be a library, more like BerkeleyDB, I really don't want an entire server. Someone could just add a server on top of it if they really wanted one. It would also be nice if understanding it (in its entirety) wouldn't represent a big investment.