Has UML died without anyone noticing?
UML's promise was that that with detailed enough diagrams, writing code would be trivial or even could be automatically generated (there are UML tools that can generate code).  It was developed during a time when there was a push to make Software Engineering a licensed profession.  UML was going to be the "blueprints" of code, and software architects would develop UML diagrams similar to how building architects create blueprints for houses.  But as it turned out, that was a false premise.  The real blueprints for software ended up being the code itself.  And the legacy of UML lives on in simpler boxes and arrow diagrams.