Aside from the in-seat power, I think another likely solution will be third parties like Belkin making a less "apple-esque" but longer lasting battery that's compatible with the magnetic connector. The OEM solution looks quite small as is. [1]
Interesting, it doesn't show a way to charge that brick. I assumed it would have USB-C for charging, though perhaps MagSafe makes more sense given the propensity of the user to stand up and start walking without realizing he's plugged into the wall!
I also wonder if it will use the other type of MagSafe (like on the iPhone) charging. I could see the argument for convenience, but presumably this would be significantly slower charging than over USB-C.
1 https://www.apple.com/v/apple-vision-pro/a/images/overview/d...