Readers Digest version from the 788 J seat thread:
- Currently 1 of 20 788's have been modified (N800AN) (5% chance you get it, scheduled between ORD and LHR for next few days.)
- No 788's currently scheduled for PAE (via publicly available schedule for the next few days)
- N811AB returned from SAT, but has not been refit (seat map still shows 28J)
In short, SAT is apparently not doubling as a refit location, and there are simply maintenance/other things going on at SAT for the 788's.
Link to N800AN schedule:
https://www.flightradar24.com/data/aircraft/n800an