I think it's possible to make a board that the buyer can fully customize. The restriction is going to be the pcb, which is a problem I and others have conquered with the teensy controller and KBC gave the idea of having a pcb drilled both for alps and cherry. Even if you don't like the pcb that we make, with the teensy controller it'll be easy to rematrix it because it's not going to have wires being strung all over like a standard board will which will allow the buyer to complete rewire and reprogram the thing if they want.
The only other restriction is the plate, which if you want, you don't have to buy the plate, but it will make it more difficult to solder, and get everything perfectly straight.
A completely customizable board is a very possible goal, as I and others have proven with my and their prototypes, and at a relatively low cost, it's just some relatively minor know-how issues holding it up. Also motivation for me. I need to put some more time into searching out cost effective solutions.
The humble hacker is a board that has been fully prototyped as well, the only issue there again is cost, but it's a model that I took a lot of inspiration from. DMW created completely customizable firmware that will run on teensy's that is amazing, which was the biggest step. So many hurdles have been crossed, it's relatively little holding it up in my mind. It's mainly just getting costs down.
I was watching a hak5darren show recently and they had a guy on there that created a bluetooth dongle that you could sniff with. He used this service:
http://www.kickstarter.com/projects/mossmann/ubertooth-one-an-open-source-bluetooth-test-toolThis might be a possibility. This would give us the money to go ahead and get manufacturers in China ect which would make it a reality.