Before it is successfull, the parts that are not swappable needs to be at a standard where no one complains, like a 1080p screen at 5 inches. The bandwidths for different modules needs to be at least 2 or 4 times the current best.
The main board should not be like a motherboard, but more like a set of pcie connection so that a generation lasts a few years just like "project christine" by razer in the modular desktop space.
Though for some reason it is being targeted at the mid budget market, I can see only super enthusiasts to ride on the wave.