What this means to you is that you must now be able to defeat three Heldrakes that don't have to leave the board! Oh, by the way, they're AV 12 with a 5++, It Will Not Die and a torrent flamer that melts your troops, which you cannot hide, either in a transport or behind a wall.
Somebody is going to bring it. So whatcha gon' do 'bout it? Well, you need IG allies for the Vendetta, an Officer of the Fleet to keep the flyers off the board, and for troops in a Chimera.
Those Daemonettes I'm so fond of fielding because they're great at hiding, then running to objectives when the coast is clear? Well, they're still ok, and can survive one, maybe two blasts thanks to a 5++, but now you really need some Plaguebearers, too because a Baleflamer will only put 1.5 wounds on five of them, meaning Heldrakes suck at killing PBs. I'll be dusting mine off.
You also need Flying MCs because if you don't kill those things with a single shot, you probably won't kill them. For that, you need lucky Bolts of Tzeentch on the rear armor. If you can penetrate, a 2+ on the damage table is all you need since that'll get you a weapon destroyed, immobilized or 'splodes result, any of which are good enough to render it mostly ineffective.
Fighting three Heldrakes at 2k points or less means a full fourth of the list is in the sky, leaving a lot less stuff on the ground to be worried about. If your army is properly-constructed, the Heldrakes should pose a minimal threat. A Baleflamer will kill 1.5 Flamers if it hits a squad of six, which is negligible. Even less if Fateweaver is around.
Quad guns are almost useless because they aren't likely to do more than glance a Heldrake, and anything manning them is going to be killed by a Baleflamer. Icarus Lascannons are the better choice in this case, but even then, you're hoping to get lucky with the interceptor shot before the dudes manning it get toasted. Quad Guns are better against most other flyers.
Bastion, Icarus Lascannon
CCS, Autocannon, Officer of the Fleet (Goes atop Bastion)
PCS, Autocannon (Goes in Bastion.)
Infantry Squad, Chimera
Infantry Squad, Chimera
Hydra Flak Tank
Most of your troops are safe from the Baleflamers, and you have enough anti-air to take care of at least two of the Drakes. If you lose the CCS on the Icarus, what do you care? Damn, I's out 90 points! The Hydra should be positioned on the board edge so that a Heldrake has to leave the board to vector strike it. Otherwise, the Heldrakes can't really hurt it. Fateweaver, Flamers and Screamers do their thing.