Gonna assume, that any option which doesn't come in the box, won't be in the book. I thought all those weapon options came in the aspect boxes though.
I've never picked up any of the resin boxed sets (when I last bought Aspect Warriors they still came in blister packs and Exarchs came in separate ones) but my understanding is that the only options they come with are the ones shown on the box. Which implies two of the 4th Ed. Exarchs 0 the Banshee and Fire Dragon - with alternate weapon options are no longer supported (I may be misremembering the Dark Reaper - it's possible that once had a model with a shuriken cannon). The Hawk and Spider options have certainly never had models, and I don't think the Scorpion did.
I can confirm Reaper Exarch still has the shuriken cannon and Dragons have the DBF option. It seems the Hawk lost both gun options as well as spider Exarch losing the spinneret rifle. Sad.
Thanks. The DBF is the only one that specifically affects any models I have, and I do sometimes use the option in part because my firepike Exarch is in another country.
I believe the official ruling from GW is that any units/options that existed in the Index books that is not listed in the codex may still be taken using the Index entry. For example, Roughriders are apparently not in the new IG codex (so I've read -- I don't own the IG book, so I can't say for sure), but IG players are still allowed to field Roughriders using the entry from Index Imperium II. Likewise, Marine players who lost Dreadnought or Razorback weapon options can still use the Index Imperium I entry for those units to get their desired options back.
I think the issue is that now these options have been officially removed, they're unlikely to return because any revision to the model range will need to be consistent with the current Codex. When the Warp Spiders are finally revised they aren't going to get an Exarch option with a spinneret rifle because they'd need to put rules for the unit into a datasheet and that would just be confusing for a unit that already has full rules in a Codex. The big issue is likely to be the Autarch, who's now going to be pretty short of options relative to most characters and whose options don't even fully support the available official models (it's been discontinued, but the Scorpion-helmeted Autarch model does have a warp jump generator).
Hmm, given that Eldar have a bunch of other ways of getting harder to hit (Rangers, Flyers, Conceal, etc) is it possible someone could run an Alaitoc army where the vast majority of the army is at -2 to hit from enemies? This seems like it would be incredibly strong, too strong imo:
Remember the Alaitoc bonus doesn't work at ranges closer than 12". All the units other than the fliers and Serpents in this list have 12" range, aside from the Rangers who have low firepower output and can't evade deep strike or enemy fliers very well. If your plan is to get Wraithguard into range with Wave Serpents, they won't get this bonus even for a turn unless you're moving second (in which case they'll take a bit less damage on their Wave Serpents but were probably going to survive anyway).
It's also an army built around modifiers that do nothing at all against close combat armies. It does help the fliers, but they could get an equivalent bonus previously.