with same results, a Frankenstein-ish laptop with compromises everywhere, and usually thicker and heaver than a store bought laptop. Now the HP Stream and Tosh Chromebook2 could have been the way to go, but some have hard soldered EmmC boards, or non upgradable memory.
Could this be done, uhhm,yah... but it will take a major manufacturer to make the base kit and still have a relatively sexy laptop.
So what we need is a great screen to start, a mother board(s) that are cheap and upgradable, extra RAM slots, and probably an M2 interface for storage, with that said, it would have to be a standard, so others can make components to fit.
I dont see this happenening as long as the main OEM's want you to buy a new laptop every 2-3 years.