Thanks for the reply! That's very reassuring.

Is this because it's a D1-marketed flight, so presumably they would prioritize keeping this D1? I feel like I've seen plenty of horror stories about D1-to-FC downgrades due to equipment swaps, but maybe because those were mixed D1/FC routes and I'd be safe on JFK-SFO (barring a last-minute change to IRROPs, etc)?

Since this is right after Thanksgiving and I've seen reports that they upgauge to a 767 sometimes anyway, it sounds like I should be able to book with relative confidence?

November is far away! The discussion upthread on that link did argue that the first conversion is always slowest and the remaining should be much quicker. Fingers crossed for me (or I guess everyone given the derision the 752/763 cabins get).