Seems to me just a nice way of saying they will not sell well.
Thats funny because most people who follow VR and those working on these products already understand that they're not going to sell like gangbusters let alone in any significant amount for a long time.
VR as a whole will be brought to many things though. LG just announced a VR headset for their new phone and Samsung is giving away Gear VR to Galaxy S7 preorders. We also know Google (Cardboard) and Apple are working on a few significant VR projects. VR on the smaller scale will do well but the high quality VR from PC and even PSVR will take several years before it becomes a mainstream success because of price and availability.
Anybody expecting VR devices to sell 10s of millions of units in the next 3-4 years are delusional.