@Rhyleth
Greetings, and welcome
1. Flyers.
Hemlock is arguably the best unit in the current CWE index. For its points it is fairly durable, versatile (being a psyker in addition to being a gunship) and has some very respectable damage output, especially with Smite (which I find myself doing most of the time lately). Coupled with the fact that it effectively (almost) doesn't degrade with damage, it makes its performance outstanding.
Crimson Hunter is a firm average performer in my experience. Not outstanding but fair. Works best when there are other more dangerous/valuable units present on the field to distract the enemy fire from it.
Flavourfully I prefer Aspects to Wraiththings, so it is a shame the Crimson Hunter's so poor, but that was certainly my impression from the rules. Also I like the Battle powers even though I'm most likely to use Smite most of the time, so acting as a Warlock is a plus. I've bitten the bullet and ordered a fighter and a Wraithguard unit, as those are what I'm most likely to use no matter what and I don't presently have the models. I debated a 10-strong WG unit, but most people seem to run them as 5s in transports.
I have a sense that like much of the Eldar range it may be replaced with the new Codex and so they may not make any more until that releases).
I most certainly wouldn't count on that. At least Wave Serpent IMO is not going to be re-released with like 99% guarantee. And people are hoping for plastic Aspect Warriors for as long as I'm collecting Eldar (which is over 15 years), but they never come. And not a single FW-designed unit for the Eldar has become part of the standard GW range so far. I really doubt that just now is the time for all those things to miraculously happen.
I doubt the Amazon prices would be so high if had been available from GW in the recent past, and the entire GW range has gone to 'Webstore Exclusive' except for Guardians, Dire Avengers, the Fire Prism/Night Spinner (which is admittedly an odd omission - while the kit has a newer sprue than the Falcon and Serpent, the base Falcon is the same model), and the models released from 4th Ed. onwards. If it were just a repackaging issue to add superfluous letters to the beginning and end of the world Eldar (I have it on good authority that the 'A' and the 'i' are silent) I'd expect those to have been withdrawn as well.
The Eldar range probably has the largest proportion of surviving 2nd Ed. models - Eldrad, the Phoenix Lords, the Avatar, Warp Spiders, the Vyper and the Falcon, as well as the base jetbikes of the Shining Spears, and likely the largest number of now-resin units. The remaining infantry is all from 3rd Ed., save the Wraithguard.
While they may not fully plasticise the Aspects, I suspect some of them will be revised; I'm not sure why they missed the chance to make the jetbike set a modular Windrider/Shining Spear set. The Warp Spiders are desperately out of date - much bulkier than any of the more recent Aspect infantry, five Aspects have been saddled with weapon options that don't exist on the models since 3rd Edition (Swooping Hawk sunrifle, Warp Spider spinneret rifle, Striking Scorpion chainsabres, Dark Reaper EML and shuriken cannon, and Howling Banshee triskele), and the Shining Spears have a weapon option that's no longer supported (brightlance Exarch - though possibly that's now just treated as a starlance since there was no separate starlance component). Even the Fire Dragons, which have fully supported Exarch options, appear to be packaged without the dragon's breath flamer Exarch, a model which may not have survived the transition from metal.
Also, GW has moved more heavily towards plastic since the Eldar were last updated, and they don't have that many models they can put out to support these 10 new Codices. Evidently not every one will receive model support, but aside from isolated characters here and there nearly every other army has recent models - multiple entire armies are more recent than nearly the whole of the Eldar range. To some extent this can be seen as a testament to how well they've lasted, but stylistic changes have badly dated some of the models, weapons are almost universally oversized relative to modern GW norms, and the Phoenix Lord models are outright embarrassing (Karandras was widely panned at the time, but none of them have stood the test of time well. Fuegan and Baharroth perhaps better than the others, in part because the redesign of those units in 3rd Ed. didn't change the aesthetic as drastically as some of the others)
While FW-originated units don't often make the crossover to GW (have any other than the Tau Piranha, for any army?), the Warp Hunter isn't any more an FW unit than the Night Spinner, the Wave Serpent or the superheavy grav-tanks - it's an Epic unit, and GW made the Night Spinner kit after Forge World already had one (they also did with the Wave Serpent, but that unit had at least been in official GW rules before the Forge World model came out).
If they don't make the Hornet, they may at least make a new unit that fills the same role, as they did when they made the Hemlock instead of any of the FW fliers (though all except the 'Vampire Hunter' and the Lynx were pre-existing units), as players appear to be demonstrating that it's a role the army needs.