I've seen a few ex-SEA on both DFW and ORD routes. Very rarely do I see them flying to JFK, although that route goes back to the 752 soon so won't see any WiFi for a while. Based on my observations here, on other sites, and in person, there appear to be four tranches of 738s in AA's fleet:
- Older purchases, with original configuration involving S80-style seats in front and Y going back to row 28; no WiFi, not in CIP configuration
- Older purchases, with updated configuration after having gone through the CIP, including articulated seats all round and Y going back to row 30; has WiFi, and is in CIP configuration
- Mid-age model, with updated configuration coming straight from Boeing, including new articulating seats all round and Y going back to row 30; no WiFi, but came from the factory in CIP configuration
- Newest models, with updated configuration and WiFi both coming with the bird as new; has WiFi, has CIP configuration
I stand to be corrected, but I'm pretty sure these are the options. So the only birds with WiFi are the most recent deliveries, and the oldest 738s that have gone through the CIP and gotten WiFi that way.