Troops aren't needed on the ground. The Peshmerga and YPG are more than capable as a fighting force, if they were armed properly. Instead of sending in troops to support the YPG, aid them with coordinated airstrikes and give them heavy weaponry.
I'm not sure for Iraq though. There are already some American boots on the ground but they're called "advisers". Troops shouldn't be needed as Mosul could be attacked in the coming weeks, and if Mosul goes then ISIS should be finished in Iraq.
Also Kobane is near complete liberation, any day now...