References to "next-gen Source 2" buried in the code for Valve's recently released Source Filmmaker indicate that an updated version of the aging game engine is a known quantity. It isn't particularly surprising to learn that 2004's Source engine is being updated, but this notable for being the first hard evidence of Valve's future plans.
You didn't really expect Half-Life 3 to run on Source, did you?
The discovery was made by a code-savvy user at Valvetime.net (via Eurogamer). There are apparently numerous references to Source 2 in the vproj.py file buried in one of Source Filmmaker's subdirectories, with one string of code in particular referring to "next-gen 'Source 2'." Icons for 'Source 2 tools' were also discovered, suggesting that Source Filmmaker could be readily compatible with the next-gen engine whenever it is released.