I do agree that transcontinental "MUPways" (or whatever else you want to call them) are inevitable. According to Machka, they are being developed in Europe. Here in America, the rails to trails movement is growing rapidly, as are the USBR numbered bike highways.
These paths are mainly envisioned for recreational uses--bike touring and longish day trips. I will be pleasantly surprised if jobs, schools and housing develop along them.
if you want to get into a migratory experience, become a traveling nurse or a locum tenens physician. These jobs pay VERY well and provide assistance with housing and travel arrangements. I don't know of any reason why you couldn't travel between job assignments on a bicycle.
http://en.wikipedia.org/wiki/United_...Bicycle_Routes