Haven't some manufacturers of PCs already tried that? Dell for one prime example used to have custom bios's for things like video cards, sound cards etc. If you wanted an upgrade you couldn't go out and buy a generic nVidia card because it wouldn't work. Instead you had to send the PC back to Dell so they could charge £/$300 for a £/$100 upgrade. The drivers were different too, so you had to go to Dell to get them (still happens a lot today). They realised how much that was hurting them once they acqired Alien Ware. Things are a little more relaxed now, I believe. I think that's where the mobile market is heading. The tweaker geek has always been a breed apart and not as well catered for by manufacturers, they're more interested in the "I just wanna take it out of the box, switch it on and use it" brigade who are not interested in what goes on behind the screen.