I'm guessing it is okay to remove the differential.getrevision and differential.getdiff endpoints? They were deprecated some time ago.

If they don't make this change harder (I think they don't), I'd very slightly prefer to leave them until T5873 / T7715. I think those are happening soon (next few months) and I'm currently looking at compressing as many breaking API changes into a small window of time as I can in connection with them (basically, make a single major revision to the API instead of breaking it a bunch of times over the next few months).

Particularly, if we remove them today, anything relying on them will need to switch to revision.query, and then be broken again by T7715. If we get rid of them both at once, clients can do a single update.