4000 point swing? Only if Roger gets bounced early on at Wimbledon, and Nadal wins it all. What is true is that Rafa doesn't have any points to defend, and would be able to put some up on Federer.
Like I say so often - 'never say never' in tennis. Sampras was considered to be 'invincible' just the same, until some little upstart named Federer bounced him out. It could just happen again. Of course, a 4000 points-swing is the most extreme thing that could happen, and I don't think it will, but the odds are a lot better for Raf now than they are for Rog come Wimbly.
Say if Rafa gets bounced in the Quarters, Federer would make that up by winning Halle.
Rafa is playing Queens, and can make exactly the same amount of points over there, as Federer can in Halle.
However, it's also true that Federer isn't defending much on hardcourts either.
Rog is defending a final at the USO, and a victory in Cincy. Besides that, Rafa racked up an ultimate ZERO points at the year ending WTF, so again, a chance for him to pick up 1500 over there. I don't think he will, but just saying.
If Federer reaches the final here, I don't think Nadal will be able to catch him through to the end of the year.
Your positive line of thinking re: Roger is admirable.