I think we all know there will be another gold rush for "social" game companies once VR takes off. So, IMHO, Zynga just needs to slug it out till FB gets VR pushed to the masses.
I think most people are in agreement that, simply from the fact that VR doesn't currently exist on the market, and the novelty factor, we're going to see a spike in VR sales and development.
The real question is whether or not this will last, and whether it has the potential to become a substantial part of the mainstream in the medium-long term.
My bet is on VR becoming more refined and better, with enough business to support a few small-ish headset manufacturers, but it will not come anywhere near, say, the scale of the Xbox/Playstation/PC install base. The big challenge is getting devs to support it - VRizing properly is not a small feat, and developers have proven very reluctant to support niche hardware (see: Kinect).
I wouldn't underestimate the impact of "social" gaming on wii's success, it was seen as accessible, casual, gaming at an affordable price. One of the unfortunate aspects of current gen consoles is that the games don't support single-console multiplayer for the most part. I have to leave an go home if I want to play destiny with my friends.
With VR you can't really share the experience so it sort of loses the word of mouth type virality that came along with Wii where you might go to someone's house and play together. Instead it's a solo experience. Even if multiple people have headsets (even more money) you still aren't sharing in the experience in any way.
The smartphone headsets are somewhat better, but still just kind of a neat trick. I don't deny that VR is plenty cool but the barriers for widespread adoption are just too high in every direction I look.
The Wii was in hindsight in the same space as Guitar Hero and Rock Band - really cool social experiences that ultimately had no sticking power. Both were a flash in the pan (to the tune of a couple years rather than a couple months, but still very temporary), and both are deader than a brick right now despite attempts to resurrect it.
But in any case, agree - VR is just too limited, too niche, and too expensive. Costs will surely come down, but by enough to get a huge install base?
The Wii was dirt cheap compared to consoles of its generation, and even it couldn't sustain sales despite having a novel but niche experience. At $600-800 VR has absolutely no mainstream future, at $300? Maybe not even then.
The PSVR is IMO the most realistic shot right now at mainstream VR - it promises to be cheaper than Oculus and Vive, and has a dependency on a medium-priced console as opposed to a high-end gaming PC. Even then, the all-in cost of PSVR is likely still going to nearing $1k.
The points you're making about shared experiences are somewhat valid in terms of, I'm not going to keep 4 headsets around so my friends can come over and play. But I feel like I experienced that problem with Xbox anyway, friends who only have 1 or 2 controllers.
And once you do have multiple headsets, it's absolutely a meaningful shared experience. There are games where you can hear the other person talk, see their avatar's mouth move as they do, move around and play games with them in a made-up environment. It is so awesome.