The RaspberryPi actually started with a huge software library: It runs Linux and its applications. Download sources and compile, just like on other Linux systems, too.
I could imagine though a pimped Amiga (AGA+Apollo core) in a joystick (with a few connectors to expand it to a full system) could sell quite a few copies - given the price would kept sane. Similar to C64DTV, but a bit more pimped.
