I seriously doubt it.
Why would they do this? If they did this, they would be cannibalizing their own desktop and laptop business.
The ipad may become "stand-alone"-esque (it already is) but, it'll never be a full-fledged stand-alone machine.
As mentioned numerous times before, it's a device for consuming, not creating.
Well, as the technology currently stands, it complements rather than cannibalizes other Apple product lines. Eventually we're going to see more of a blur between the product lines - and at a broader range of price points.