It's too clumsy. If you aren't gonna walk with it then it's 360 display that makes you vomit, and if you are gonna walk with it not every consumer has huge empty room where that's feasible. Most of us have couch or desk at home where we consume media, not empty warehouse. I predict whatever Mozilla thinks they are doing it will fail for the same reasons Google Glass failed spectacularly or why after years already spent on VR I don't see anybody outside koolaid-drinking techies owning one set.
Mozilla has one good consumer project that can realistically be completed (browser in type-safe language) and getting the team behind it bogged down with tech that's immature and doomed to failure is unfortunate.