Just to clarify a little: This bit of fiction would be Half-Life 2: Episode 3. The Episodes were billed as essentially Valve creating the much desired Half-Life 3 without the normal 6 year development time associated with a full sequel. The problem is Valve promised three episodes and only delivered two, leaving us all in the lurch.
The last paragraph of Laidlaw’s synopsis is pretty great in my opinion. It can be interpreted as him passing the torch to the fans, calling on them to create their own games in the Half-Life universe, and his synopsis leaves a lot of opportunities for that.
Well seeing as he and all the other writers involved with Half-Life are no longer with Valve, that’s pretty much a given.