There no technical handles or issues to make a Fanless Laptop. Get it low enough Clock speed Broadwell is there already.
The problem is.
It will be slow, definitely slower then previous gen Haswell if it were to go fanless.
GPU will suck, Graphics performance suffer quite heavily.
And finally, ALL ULP Intel chip are extra expensive. No way could Macbook Air continue to sell at this current price range, especially with the rumors Retina Display.
All in all, the...