This isn't really a Hacker News-worthy subject, but since we're all here, I would interpret this news as an indication that the most destructive, norm-breaking impulses of this administration are yet to come. If you're planning something so absurd that even Barr won't go along with it, you know it's going to leave a mark.
If I had to guess, I'd say that Barr will get appointed Special Counsel for something or another.
Assuming he hasn't decided to retire completely, the likeliest scenario to my mind is he'll get pulled in as Attorney General for the next Republican President to come down the lane.