The most obvious use case to me is the ability to have the equivalent of multiple monitors condensed into a pair of googles that you can easily bring around with you (women can even slip it easily into their handbags).
The Vision Pro is an alternative to a computer (actually it's a solution to iPad multitasking), not a multi-display peripheral for a computer. People keep thinking about it as if it does what their fantasy of computing would do, when it doesn't.
It's analogous to the iPad, which went years of not being the device people thought it was going to be, by not having a proper stylus, or filesystem (or the Mac-like cost people were expecting). Finally, Apple threw in the towel and made the iPad Pro, which is what it should have been from the start - a version of Microsoft's Surface Pro, albeit giving it a better drawing experience, but being a worse computer.
I assume someone like MKHBD could travel overseas with a 16" MBP and Vision Pro, then once he has a chance to sit down, plug in his Vision Pro into his Mac and get a larger display that he can edit his videos on. This doesn't even need to be back in your hotel room, anywhere with a desk and chair will suffice.
Which he won't be able to do, because the Vision Pro only allows a single-screen mirrored wireless VNC remote connection to a Mac.
It doesn't let you abstract your Mac's apps so that you can have an editing window, with separate free-floating palettes and gesture control etc - what it offers is exactly what VNC offers on an iPad, when you Mirror the Mac's display. At present, it doesn't even add anything to the Mac (as far as I've seen), the way the iPad adds a drawing tablet function with Sidecar
It's not going to provide a larger screen, in terms of pixels, for the Mac than a laptop's screen - in fact it will be significantly lower quality because the pixels of the Vision Pro are distributed across the full width of the user's field of view, rather than being concentrated within the narrow field of view of the laptop's screen.
It also looks like it could be the ultimate consumption device. Imagine sports being streamed in spatial video, and viewing it felt like you were there at the stadium itself. In theory, if this can be done right, you don't have to put up with constantly switching amongst different camera angles. If I want to see the score, I can just turn to my side and look at the scoreboard. It could even extend to concerts and other live events.
This is the thing for iPads - despite all the attempts to make them Computers, they remain consumption devices with some niche creation cases, usually created by denying drawing tablet functions to the Mac's screen - if Macbooks had the iPad touchscreen and could use the Pencil, probably the majority of the iPad Pro's sales would vanish overnight.
Go into any medical professional's office, especially mobile therapists, and they're using Surface Pros because iPadOS has too many roadblocks to be a general-purpose computer (I tried it for months).
I don't think the Vision Pro will have the onboard power to do tasks that people think a headset will enable for content creation, and I think it's going to be as annoying as trying to make an iPad your only computer.
But as a rich person's toy for interacting with Apple's in-house iCloud apps - Facetime, content viewing etc, that's probably the sweet spot.
There's also the potential for interacting with AR without needing to constantly hold my phone up. In short, the vision pro makes sense in any scenario where the smartphone is suboptimal.
I don't think the Vision Pro is going to have the tools to make AR content in AR/VR - I think it's going to be a viewer, but pople making content for it are still going to use PCs, the same way people making games for Apple platforms (Apple Arcade etc) do that overwhelmingly on Windows.