The skeins of fate seem to be pointing at Eldar in June, so I figured I'd give a rundown of the things I'd like to see in the new Codex.  Obviously I have no advanced knowledge of what's going to be in it, so this isn't even speculation - this is simply what I'd like to see.

Misc

  • All Aspects: Allow any number of models to be upgraded to Exarchs with access to powers and wargear.  Allow Falcons as Dedicated Transports. Give me 3 different boxes that have 10 models each which can be built as Striking Scorpions/Dark Reapers, Fire Dragons/Howling Banshees and Swooping Hawks/Warp Spiders.
  • Everything: Deny the witch on 5+ because they're all psychically potent.

HQ

  • Phoenix Lords - unlock their aspects as Troops choices.  Maybe an invulnerable save?
  • Autarchs - ability to pick warlord trait instead of rolling.  Some other awesome army-wide buffs. A plastic model similar to the Space Marine Captain Sprue.
  • Farseers - two different farseer paths - Farseer and Warseer.
    • Farseers get the current disciplines, Runes of Warding, and maybe some army-wide defensive buffs.
    • Warseers get more combat-focused mind toys, 2 attacks, access to cool weapons, and maybe some area-wide offensive buffs.
    • Allow each HQ slot to hold 2 Farseer/Warseers because seriously, more psykers for what should be the best psyker army in the game.
    • Let them cast out of tanks because tanks are made from psychoreactive Wraithbone and you'd think they'd have figured that out sometime in the past 20,000 or so years.
    • Just like the Autarch, a plastic model to let me build the Farseer I want.
  •  Warlocks - include powers in their price (maybe a small increase?), allow them to upgrade witchblades to direswords.  Make them splittable like Wolf Guard. Plastic models.
  • Avatar - Monstrous Creature-sized model, ability to take the Court of the Young King, Eternal Warrior, It Will Not Die, and have it grant Furious Charge within 6".
  • Eldrad - Mastery Level 4, generates 6 powers, everything else remains the same. No, seriously, this should happen.

A Harlequin HQ that unlocks Harlies as troops.

Troops

  • Storm Guardians - I don't even know what you could do to make these viable.
  • Guardians and Guardian Jetbike Squads - Maybe a few more toys like special weapons and/or a power weapon or something. Other than that, they're good.
  • Rangers - precision shots on 5+ and BS5. Plastic models
  • Dire Avengers - Aside from the Aspect note above, Dire Avengers are pretty good as they are.

Elites

  • Striking Scorpions - Give them back their first-turn infiltrated assaults.
  • Howling Banshees -  Give them an assault vehicle maybe? I could accept the AP3 nerf if I could get them where they're going without dying.
  • Fire Dragons - Let them trade their fusion guns for Dragon's Breath Flamers. Also, some neat extra fun if they get multiple "Explodes" results when popping a tank.
  • Wraithguard - Models that don't cost $15 each and come in groups of more than one.  Also, make Wraithbone a 4++ and no armour save.
  • Harlequins - I doubt these will change, considering they're identical in the Dark Eldar codex, but maybe a note that they count as both Eldar and Dark Eldar for all alliance purposes?

Fast Attack

  • Shining Spears - something to make them worthwhile.  Also, a kit that has Warlock and Farseer parts as well.
  • Warp Spider - These are actually pretty good as they are.
  • Swooping Hawks - Let them assault Flyers, even if it's only on 6+, and give them something better than the looted lasrifle they currently carry.
  • Vypers - Just vehicle upgrades that I'll discuss below
  • Obviously a flyer or two.

Heavy Support

  • Support Batteries and War Walkers - no real need to change these.
  • Dark Reapers - these are good, too.
  • Wraithlords - These do very little well for what they are.  They're the finest warriors brought out of slumber, and they're just OK at shooting, and not very good in assaults other than their size.  Here's what I'd like to see their stats at: WS5 BS5 S8 T8 W5 I5 A3 LD10 Sv- (4++).  Also, no more twin-linking for buying two weapons. Give them the ability to be really shooty or really combat-oriented.  And a really cool MC-sized model would be nice.
  • Falcon - As I said above, make it a Dedicated Transport for Aspects only, and give it some way to become an Assault Vehicle - like a micro Warp Gate inside it or something.
  • Fire Prism/Night Spinner - Drop to BS3 (keep reading)

Dedicated Transport

Wave Serpent - I'm fine with this as it is. Changes can be made with upgrades below.

Fortification

Haven't seen any of these in the new codexes, which is odd.  I figured at least Tau would get something, considering all the ones in the rules are completely Imperial. I'd like to see something like an ancient Warp Gate that allows the entire army to be held in reserve, allow all units to deep strike with no scatter within 12" of it, and start rolling on turn 1.

Vehicle Upgrades

  • Crystal Targeting Matrix - bring back shoot and scoot!
  • Spirit Stones -  should become PotMS instead of Extra Armour.
  • Warrior Path pilot - Upgrade to BS4
  • Scything Blades - All assaulting models take an auto-hit at S6, AP 5. If a skimmer moving 36" a turn can still be assaulted on 3+, it should at least hurt.
  • Star Engines - need to come down in points now that they're just an extra 6" to flat-out.
  • Holo Fields - change to granting a +1 to their cover save (6+ in the open).  4+ Jink saves would be awesome.

Now, to be fair, I've had some good success with my Eldar now that I have a good build worked out.  The only problem is that there aren't a lot of good builds anymore.  I'd like to see that improved.

For Holy Terra - Because space is scary