Check this out, by far the most comprehensive rundown of events since at least HL2 and how that all transpired to the current day.
I think the two scenarios he proposes both hold solid ground. On one hand what if it is a social experiment by Valve, a feeler if you will to gauge how loyal fans of HL still are. Laidlaw is said to still be in contact with members at Valve, and given how secretive Valve have been over the years about any story development on the HL ep3 front, I can't see them allowing something like this to slip through without consequences.
I think we've not seen the end of this yet.
At least one thing is clear, we know Valve are working on HL VR, because Gabe has mentioned it numerous times. Whether this means HL3 is a VR title, or a completely new story in the HL universe is anyone's guess. As for Episode 3, well that's what we're all trying to figure out.
It would be extremely foolish to abandon HL as it's one of the most successful game franchises in history, every "leak" makes the internet go crazy. I do think Valve won't release anything until all platforms are ready. We know they are more focused on money now than back then.
So what are they waiting for? Perhaps they want console platforms to be up to PC levels of power and VR performance, so all platforms can have a release of what they are working on at the same time, with the same quality. Total speculation of course but maybe this is a good thing?