I think the value of the technology hasn't reached a point where it exceeds the inconvenience of using it; namely the bulky headsets and expensive hardware. I agree that it won't be more than a niche technology in the near term future. I guess it all depends on how many more orders of magnitude we can expect to get out of miniaturization before we hit the wall. If it's possible to get a minimum of 4k per eye resolution and the graphics performance of a 2017 high end gaming GPU into a pair of wraparound sunglasses combined with a smartphone, I see it becoming the dominant display technology. The convenience of being able to summon any number of arbitrarily large displays at will is hard to deny, even if you completely disregard any value proposition involving AR and new forms of human computer interaction.

I'm sitting in bed with my laptop right now, and if I could choose between reading this on a pair of lightweight glasses or my laptop, I'm not sure what the laptop has to offer. The big issue is touch typing; no (macro) gesture-based virtual keyboard is ever going to be usable for professional workloads. I sometimes wonder if some kind of one- or two-handed finger-chording input could be as efficient as a qwerty keyboard. I would be willing to toss my decades of qwerty experience if I could eventually get something as fast without having to carry around a keyboard. I imagine something like this device from Children of Men: https://youtu.be/sJO0n6kvPRU?t=2m4s (1024 "keys" should be plenty, so it's technically possible).

Regarding direct brain-computer interfaces, I just don't see the technological barriers going away any time soon. You'd either need some type of non-invasive technology that could wirelessly stimulate the optic nerves (aside from light, obviously), which I'm not sure exists even in theory, or such sophisticated nano-machinery that it would be effectively invisible, like a neural lace. I don't see either of these things happening for decades at least (I would love to be proven wrong though!).

I don't know if the form factor that will finally trigger mass adoption will resemble currently available headsets. The breakthrough might be retinal laser projection or light field displays. I just think that if nothing else, the ability to move our current workloads to a portable virtual display is such an obvious improvement I can't imagine it not happening as soon as the technology is good enough. Of course the same can be said for BCI but that doesn't even work in the lab yet.