Anecdotally it feels like VR never really took off? From casual perusals of the steam store at https://store.steampowered.com/vr/, there are very few VR games and the ones that do exist are fairly mediocre looking - things you've never heard of from indie developers self-publishing to steam.
Seems like an odd move from Valve - I don't suspect that this on its own will be enough of a draw to lure people to purchase a VR headset for. Especially since this started out as an "exploration of VR" ... I am left wondering if this is basically going to end up being some glorified DLC or mod that adds a couple of levels with a few neat little VR-specific touches/gimmicks rather than a full-blown installment in the HL franchise?
They may well prove me wrong and trigger a renaissance in the VR gaming industry and wow us with a huge and well-executed sequel to HL2 that will lure people in, but I remain skeptical for now.