He's found many more references to a "Source 2", but not just one vague line like our previous entry. We're only one file deep, and already it's clear that the references to "Source 2" are indeed referring to a next-gen engine that Valve is currently developing. I'm only going to show one line in this post, but there are about 60+ references here, and this one line is probably the most telling.
The Pastebin & file path:
'''Return an str with the current engine version.
If key doesn't doesn't exist, assume 'Source', otherwise invalid -- assume next-gen 'Source 2'.'''
There are references to Source, Hybrid, and Source 2 in this file. We speculate that Hybrid is the base for which Source 2 is sitting on. Barnz also says it looks like Source 2 is using the same pipeline as Source, meaning that it will probably be keeping its .BSP level format. We haven't found any references to DirectX or OpenGL yet, or Episode Three for that matter, but we're still investigating.
The Ep3 reference from before was just a comment, so it's unlikely we'll find any more mentioning of it. Source Filmmaker was in development parallel to Source 2, hence why these script files have so many references to the new engine.
Valve wants you to know that they "don't like to brag, but Source is considered the most flexible, comprehensive, and powerful game development environment out there. And it's about to get even better."
We'll keep you posted if we find anything else! Or if you come across some new stuff, we'd like to help you share it with the world, so you can submit any findings to firstname.lastname@example.org