I was hoping to see something like this, though I didn't know what form it would take.

A few months ago I was at a demo night in SF and 4 people demo'd essentially the same tool for managing PRs. At the time my thought was "are we really going to be dealing with PRs in 2 years.

I don't know if Delta is the right solution, but Zed is at least questioning the current paradigm, which I think is important.