For my purposes, THIS is the killer app, as relatively simple as it is vs. the great stack of potentials of high resolution VR/AR.
All one needs to do is switch from a large, expansive Mac screen to a relatively tiny 16" or smaller and miss the larger screen R.E. to want a remedy. That remedy is NOT building even bigger laptops, or laptops with screens that fold out... or roll out. For most of those options, it would add a LOT of weight. This doesn't. I envision a new kind of laptop usage here: laptop + Vpro in the bag... and maybe a lidless MB and Vpro in the bag.
And like laptop screens, this is an any-size screen you can summon to use wherever you happen to be. In my case, a major use will be on long flights where cramped seating spaces sometimes doesn't even allow for a laptop to be used in the normal way (can't fully open it at the normal angle to use it).
Bummer that one can't summon multiple Mac screens in the overall view. However, since it is projecting ONE Mac screen and since Mac easily manages multiple screens in Spaces, leave the heavy lifting to Spaces by opening any number of Mac apps across any number of Spaces and then switching to alt Spaces when you want access to those other running apps in the Vpro view. You can basically fake this right now by air-playing a Mac through AppleTV to your big-screen TV. Open up any number of Spaces, run Mac apps in those Spaces and then switch to them via Mission Control as desired. That same thing should work the same way with Vpro (minus the AppleTV need).
Very common apps that I will want to use WITH some Mac apps are Mail, Safari and Messages. Since those are native apps that work fine on iPad, they WILL float next to the one Mac screen. So instead of running them on Mac or on a Mac Space, I'll run the iPad/Vpro versions of them and float them around this Mac screen, switching to and using them as desired and then back to the main workspace. The whole Mac virtual canvas could be owned by some key Mac app while collaboration via texts or email can be flowing around that view... and/or research via web can be done in Safari floating around the view... and/or copy could be polished in the Vpro version of Pages... or calculations fleshed out in the Vpro version of Numbers, etc.
Everyone who wishes for a MB 17" or MB 18" or MB 20" can get a variation of that want met here... along with a MB 24", MB 27", MB 30", MB 40", MB 50", etc. Anyone who has flown and watched the movie on any puny screen (phone, iPad, laptop) and wished they could watch it on a bigger screen, can basically have their biggest big (TV-sized) screen with them in that small seating space too, able to deliver video via this headset, like delivering music in the same setting via headphones.
Since my flights are often LONG ones and 2 hour battery life will not outlast the flight, I anticipate resolving that issue the same way I resolved the very same battery life with my original Powerbook G4: I'll buy & carry a couple of battery packs. If there is a socket on the plane, I'll use it. If not, spare battery packs will make it work until a G4 evolves into an Intel or Silicon (battery life) MB in future versions. My guess is OWC-type players will offer third-party, improved batteries soon after this thing is in the wild.
If it does this one thing really well- that is, it delivers a sharp, super-sized Mac screen for all those situations where having access to an actual larger screen can't work (which is pretty much all situations where I'm using a MB), that's good enough for me, regardless of what else it is able to do. Several of the cheapie, low-resolution ones can already do this at so-so virtual screen quality. Hopefully, 4K-per-eye delivers an outstanding Apple screen quality.
Make no mistake: I do NOT see this as a REPLACEMENT for desktop screens where Vpro becomes my ONLY screen. So all of the collaboration around a screen, etc, issues still get facilitated in traditional setups. However, in all those solo use of laptop scenarios where it's just me hammering out some project, much more screen R.E. will be extraordinarily welcomed. I feel far more productive on my 40" desktop screen than any 16" MB screen. I'm hoping this allows a 40" (or larger) virtual screen to easily go with me when I'm away from desktop settings. No way to easily accomplish that in actual reality (no easily carrying a 40" desktop screen around, balancing it on a tray table, powering it on the airplane, etc). But Vpro will apparently make this easy to do in a relatively light-weight, portable package in the same laptop bag.