http://www.theverge.com/2017/3/23/15034344/apple-iphone-ipad-laptop-dock-patent
The A10 chip performance is on par with the fastest 2015 MacBook Air or a 2013 MacBook Pro/I5 according to what I've seen. The PC "shell" could have options for extra battery and storage, or extra graphics capability. So on the low end you have a decent MacBook Air, on the high end perhaps a couple year old MacBook Pro for a fraction of the cost for a new one.