I don't think silicon is going away anytime soon. Intel and IBM just extended the the currently used processes another couple of orders-of-magnitude with another form of silicon as an insulator.
Nano technology is just building the same stuff from the bottom up, instead of the top down.
Carbon is making great strides since "bucky balls" have been synthsized, but more in micro electro-mechanical systems(MEMS) than electronic switches and amplifiers.
I think the newest technology that we will have to deal with is photons instead of electrons. The ground work is layed with lasers and fiber optics. (It did take something like 30 years to get the first practical laser working). Now they are very close to using optical communications between chips instead of electrical connections. I expect we will be seeing the first of these within the next few years. PCBoard makers are already trying to figure out how to integrate optical pipes into their boards to facilitate this move.
I think it was IBM that just announced they can now make a laser with the same processes they make digital ICs, on the same chip. There has long been work on optical switches as an alternitive to electrical switches in ICs.
Photonic technology has been very very slow in comming up, but we are starting to see exponential growth in the technology.
I do see spintronics as an augumentation to existing technology, but I think it is really more a data storage and transfer medium than usefull for processing and control.