I'm assuming it's still not complete because there's still no news about a developer SDK (I'd assume they'd love to rake in engine licensing as soon as possible)

>Furthermore Source 1 didn't really get outdated as such, it got iterated on numerous times before introducing Source 2, which I assume will not be "completed" until Source 3 gets named the next version.

The main outdated thing about Source 1 is the authoring tools, which haven't changed much since Half Life 1 was released. Source 2 is supposed to fix that.