> Doesn't the sandboxing and limited access to the file system get in the way?
Why would it get in the way? Any video editing software on it's going to be designed with that in mind, and will share with other video-related software just fine. Lots of desktop video editing software (Premiere, to pick one) start with "OK, step 1, import all the clips/videos for this project into this program" so even in the worst case it's gonna look a lot like the same workflow as video-editors are used to, and those workflows exist and became the norm on desktop before iPads even existed.
> Can you export video to non-Apple formats
Of course. Why wouldn't you be able to?
> collaborate with other people via a version control system
Never seen it for video editing, including when I worked at a video production company, though that was years go so maybe version control's normal even for amateurs and small shops now? If it's around and popular I'd be surprised if there's not "an app for that" or it's not built-in to some of the higher end editing software on iPad. If things still operate like they used to then you're talking a NAS shared over SMB for largish projects, or Dropbox for smaller ones, for collaboration, probably, and both those are fine with iPads.
> easily import footage from non-Apple devices
Sure, why not?