Valve couldn't have released Half Life 3 as a VR title. It would have made a lot of people angry seen as a minuscule amount of people actually have VR gear (unless i am wrong).
I would have hoped that by now this VR fad died away already. At best this is a very niche gaming genre, at worst VR is a gimmick.
I doubt VR will go mainstream, the idea has been around for a while and there is a reason it was never popular.
I think this Alyx game will be a generic typical VR shooter with great valve polish, it will bring nothing new to the table and will be quickly forgotten. It will not be enogh to push any other game developers to devote enough resources to produce quality titles nor will it force larger adoption of VR.
Valve VR hardware, PC steam boxes, Artifact, againt unless I am mistaken, I think all of them failed as projects. The company is clearly out of touch, their main busienss is steam store now, not game development.