If more powerful means putting back a fan, I wouldn't even want that. I have the retina macbook currently and the screen is just a bit too cramped which I manage, but the battery life is far worse than the 13 inch MBA.
I think the 4.5W chips sound very, very attractive for a low-power fanless design. Especially for a design that can burst single-threaded to 3.6 GHz. And, do sustained 4K video decode. With 4.5W (!)
Wake me when they put cannonlake on macs
Intel made huge leaps with previous generations (e.g. Core2 and related Xeons) to Nehalem/Westmere/Sandy Bridge. I don't expect to see that again. Improvements from Sandy Bridge on have been incremental. If you are waiting for another giant leap, you may wait forever.
In the meantime, the specs are now on Ark:
http://ark.intel.com/products/codename/82879/Kaby-Lake#@All