A lot of code is 1-2 years old.
Though I'm happy that mitrhil.js lives and is being developed (not just maintained). I only wish it wider adoption.
The "not completely dead" was meant to be somehow tongue-in-cheek.
v2.0 is coming. Breaking changes are minor stuff. Migration of my very large app took me about an hour. The API of mithril is pretty much settled, which IMO is a good thing. We even plan to remove stuff for next major. Simplicity is key.
That's a rather un-generous description of a framework under active development with an active community.