I use GitHub because that's where PRs go, but I've never liked their PR model. I much prefer the Phabricator/Gerrit ability to consider each commit independently (that is, have a personal branch 5 commits ahead of HEAD, and be able to send PRs for each without having them squashed).
I wonder if federation will also bring more diversity into the actual process. Maybe there will be hosts that let you use that Phabricator model.
I also wonder how this all gets paid for. Does it take pockets as deep as Microsoft's to keep npm/GitHub afloat? Will there be a free, open-source commons on other forges?
> and be able to send PRs for each without having them squashed
Can't you branch off from their head and cherry-pick your commits?
Personally, I'd like to go the other way: not just that PRs are the unit of contribution, but that rebased PRs are a first-class concept and versioning of the changes between entire PRs is a critical thing to track.