Based on my experience with automotive lighting, I do think you will see LED headlight take over the OEM market. You see, HID technology is actually quite old at this point. An OEM quality HID system from Panasonic, Denso, etc.. the cost and complexity of those systems is pretty much fixed and has been reduced to about its lowest point.
LED technology is still rapid advancing in terms of performance, and most importantly, cost down manufacturing. The driver electronics for LED's is much, much less complicated than the electronics for an HID bulb. And at this point, 1000+ lumen LED emitters WAY less than a Philips D2S HID bulb.
OEM's are just learning how to integrate LED emitters into headlights. Its a very different challenge optically, but many companies are using them now. As mentioned above, some of the most basic cars like the Toyota Corolla have them. An there are probably 20+ other vehicles from other OEMs which are doing LED headlights now.
I have personally been working on an aftermarket LED headlight kit for over 3 years. Something akin to buying an aftermarket HID kit. LED has several advantages in terms of dealing with all of these electrical issues on vehicles like the RAM. But getting HID levels of brightness reliably is no easy task. Its much easier to design a complete headlight housing or LED projector than it is to design a proper LED headlight bulb that will give the correct beam pattern in a halogen or HID housing.