As you can see, over the past 2 years we've gone from 0.36% of Steam users having a PC VR headset, to 0.89%.
We're also nearing the launch of the next generation of VR headsets. Both Vive and Oculus have products in development, and its rumored that Valve is working on a new headset as well. I expect we'll be seeing the launch of a few new headsets over the course of the next year.
So no, VR isn't dying on the vine; it's just taking longer to reach maturity than some may have expected.