Coils makes sense, considering what we saw in 5.5 with the Meracydian dragons, and also anything related to the Twins and Louisiox. It's obviously something that's coming full circle. The Ragnarok class ships is a good call too.

Omega will obviously be touched upon, but how much and how in depth is the question. There appears to be a new form of Omega that, if judging from past Benchmarks, will turn out to be a world FATE boss. So it's going to be linked to the overall lore of Endwalker in some way, but not tied to the core plot because it's not mandatory.

Alexander has me stumped though. I'm trying to think if there's any parts of Alex that aren't intrinsically linked to time travel in some way, but are more about Sharlayan in general.