Don't lose hope y'all! Flying Purple Spaghetti Monster might work for us a miracle! Believe in the you who believes in Gee-Dubayew! (Bwahaha...I'm so witty and rhyme-y!)

Bro, I'm totally for them getting the upgrade to Flyer (Hover) as an optional switch in game. Not to mention my tau are in the same boat.
IIRC, In the beginning of "Firewarrior"(PS2), your character gets transported to the planet surface by a freaking chinsy Devilfish from SPACE for crying out loud. Maybe it was an Orca, I'm not sure.
I think It totally appropriate and reasonable to allow the player to dictate on her/his turn, during the movement phase only, whether the unit will function as a Zooming Flyer, Hover Flyer (if apropriate), Skimmer Tank, or if the unit has the option, a Stationary Landed Tank, and that that 'status' if you will sticks until the next movement phase. I apologize if you don't like it because you think its too difficult to deal with as an opponent, or if you think its to much capability for one model to have, but it is how the race wages war! The Eldar should be fast and unpredictable. You guys agree that it
is the fluff.

So then how do you balance it or price it accordingly? If you give it the option to Fly, it gains Skyfire anyway, right? Seems legit. Has to be in lets say "Dogfight Mode" to go after flyers, awesome. Can't do it on ground. Cool, so "Guardian mode," for those who get the reference. (JUST realized every other letter in 'reference' is an 'e', and its the only vowel used. Standby. Brain explosion in process.

)
As for cost. You might not need to do much. There are two ways I could see it go(Most likely more than that):
1.) The option to fly or whatever is worked into a wargear upgrade. Like engine afterburners or some such.
2.) The model gets a marginal price increase according to game effect, not just flying ability. Because lets be real, whatever "Mode" its in, it still has a weakness
somewhere. There is at least hope that as it is landing to set down troops or dodge in to terrain(somehow) to avoid another flyers shooting, that it will be vulnerable for a turn. Maybe...
At the end of the day, I'm still not 100% for flyers even being in the game in the first place. But if they are going to do it, and they have and have to keep it now, we can at least demand they do right by the players and work it in appropriately to the background of the game. If nothing else could we get these units FAQed into flyers until they release our new codex for Tau? Firewarriors sitting behind a Aegis line looks silly and frankly, wrong, to me. And being the only
real way to stand up to my buddies Death Ray-Doom Scythe-Thingy, is a real groin shot from
GW.(
BTW. Due to unanimous vote, and after only a one minute discussion, the "Death Ray" was banned from our table tops until further notice. And it was at Necron-slinging-Buddies behest and recommendation! He's a Bro like that.)