One potential pitfall:  A lot of the old standardised machines (C64, Atari 800, Sinclair Spectrum) were huge successes because they WERE extremely standardised.  It's a fixed target, almost like a console, for a developer, and it ensures that everyone gets the same performance experience on their machine.  The first C64 ran off the assembly line just as people were first offering 8MHz 8088 XT clones, and the last one competed with 33MHz 486DXs.

 

I worry what happens when it becomes cost effective to make generation 2 of the $100 laptop better than generation 1.  Or alternatively, if they hold the line on features, eventually the price will tick up as you have obsoleted parts still being made solely for them.