They won't do that.I don't think going thinner is the issue, as long as they make them easier to hold without them slipping out of our hands.
Why? I long for the day the iPad could be as thin as a paper. I use my iPad Mini instead of the iPad Air ONLY because it's way lighter and I can hold it with one hand for a LONG TIME without feeling any pain. Try doing that with an iPad Air...Yeah, heavier and thicker please.
+1 Actually as thin as the iPad Air is today it's all right with me. I just want it to be much more lighter.I disagree with everyone wanting it thicker. If people want thicker, get a Surface.
Just keep doing what you're doing Apple. I will gladly welcome a thinner iPad Air 2.