They would be crazy NOT to make a new HL. They would make SO much £££.
However back in the day they said they where going to go episodic. They haven't even finished that yet! Where is episode 3?
What do Valve employees actually do? I know the hardware side will be doing something but the rest of them don't seem to do much. Are they all just working on DOTA and TF2 hats or something? They sure as hell don't do much in the way of curating their storefront anyway.
Steam/Valve are the keystone for current mainstream PC gaming as we know it. I don't get how anyone can criticise that!
But with all those resources and a mountain range of money, you think they'd knock out the occasional game as well. Fact is that Valve are no longer a game development business, but they've not told anyone.