My expectation is that they won't explicitly announce an end to support, instead the launcher will update and then cease working on these older versions of Windows.
Sorry I did not had the energy to calm down and research how to undo this shit.
Anyways, get a copy of bootcamp and black mesa, then enjoy half life in all of its updated source 2 glory
I just wish a simple thing, I close a laptop for half a year and when I open it it should work, same if I open a 20 years old PC and want to run Doom it should not prevent me to do it because some developer used Chromium for it's interface and now they are too lazy to provide paying customers a way to use the shit they bought/rented.