That is true enough. Still I think their command structure is the issue here. Their workers can do what they want to do. That means in most cases new and exiting project for them. I bet near nobody there wants to do another HL. For that reason it will likely never take off.A bit over the top to proclaim that nothing can happen with such a structure. They have demonstrably been able to adapt quickly to quite a lot of things and get a whole lot done, whether that was reacting to Win 8 and hardware, VR and the poaching of their own staff as Oculus became more distant, Controller developments, their own games as a service etc. The article of one source isn't even necessary. The simple fact is HL is not a big priority right now as a game or it is under development in some form internally in a very experimental manner. The HL film is also way off by the sounds of things with the focus on Portal. It's that simple.
HL2 took 6 years to make. Together with Source. Source 2 is "complete", but only in-house atm. It took about the same time as well. They have not announced anything about it and any titles. Dota got it added with very little fuzz. When Source was done. They showed off all their tech. Now there is nothing. No info, no PR. Just; - Dota 2 got it in an update.
At least we have Black Mesa coming this year with the Xen update. The game was already better than most fps games the last few years in 2012. And I bet it stil holds up perfectly today.