I would like to be able to import and replace whole wiki pages with text files from a Git repository. Is this a feature that would be a useful addition to this extension?
Topic on Extension talk:Git2Pages/Flow
If you want to manage some pages on Git with full histories, why not, but what's the root problem you're trying to solve?
I'd like to be able to have a set of templates, help pages, and system messages in a Git repository and deploy them to different wikis. I'm imagining a Special:Git2Pages page that lists available repos and the pages in them, and with the click of a button would update the relevant wiki pages. The reason for doing it in Git is so that multiple wikis could send updates to the pages to the Github repository (the workflow of that process I'm not sure of yet, but for now it'd be nice to be able to pull the updated pages in).
If there is a need for bootstraping and seeding, I'd suggest we could add to the extension a Special:ImportFromGit to create pages.
A full syncing will be hard for the extension users as you need to ask to resolve merge conflicts, which could be as at edit time or in a subsequent process post edit, with a need to notify of issues (through Echo, notifications are convenient now) and ask a solution.