Reading some of the tweets of the team, it looks like they will be trying to have a special edition controller.
Outside of that, the gamepad is a lot more flexible than you think. Derek Smart managed to get it to work for one of his sims that came out on 360 (yes, he actually accomplished something). Gamepad wont be as immersive as a stick but it can definitely hold its own. I used one for MW Living Legends mod and it worked fine.
Theres also several sticks on the market for the 360. The best one came with the last Ace Combat title.