SuperData has an excellent free new report of game industry sales for 2017, which includes the most important figure forecasting the future of the virtual reality industry: In three words, worse than slow.
In many more words: 2017 sales of "full VR" rigs were flat or even negative, with Rift shipping slightly more HMDs in 2016 than 2017, and HTC Vive shipping less last year than the year before.
Far as mobile-based VR, Google Daydream also saw slower shipments, as did Samsung Gear. (Though Gear VR remains far and away the market leader, with well over 8 million total shipments).
Looking at SuperData's data, the only unambiguous success in VR hardware sales goes to Playstation VR, which nearly doubled in shipments from 2016 to 2017, earning just under 2.5 million total shipments last year. (Which still means only 3% of Playstation 4 owners bought the VR headset it was created for.)
Hopefully these numbers start causing alarm bells to go off in the VR industry, because they promise a fallow season for many years to come. Personally I expected VR headset sales to grow slightly in 2017, so I'm pretty surprised to see them go down for 3 of 5 leading rigs.
I'll give the final word to SuperData, which reports these bad numbers as tactfully as possible: