This is feasible and would be a good future, just like the future we live in now where USB has replaced serial ports, parallel ports and PS/2.
https://secure.wikimedia.org/wikipedia/en/wiki/PCI_Express#P...
I know, I know: Thunderbolt is the last time people will have to throw out all their things and start over. This time really will be the last time because it is a new standard to rule over all, just like NuBus was.
And it's definitely not going to be dead on arrival like PCI-X, or not supported by drivers on the Mac for most peripherals like PCI-e. No, Thunderbolt is going to be truly universal and forever lasting world without end. If only you believe, amen.
Even many major consumer electronics are still developed via a serial console. Sure they have fancier connectors to talk to your PC and the network but serial is so simple it's practically idiot proof. So it breaks far less often, makes new hardware much simpler to bring up, and it allows you to debug the fancier interfaces without interfering with their operations.
Still not crazy about it as yet one more connector for mass-manufactured devices, though.