IMHO - The era of the motorcycle will NEVER be over. At the very least, vets, guys like me, will come home from the wars and buy motorcycles. The same spirit that the cowboy has - the yearning to be alone with the elements, wind on the face - won't die out. Those who crave freedom will always be able to find a measure of it out on a motorcycle; no matter how whacky our government gets. And just like guns, if motorcycles are outlawed, then outlaws will still own motorcycles.
My prediction is that even with all the changes and fads in automotive technology, long after the last combustion engine car has rolled off the line (probably in Mexico), some company (Triumph and that American one maybe, or some independent stubborn holdout)will still be making cycles with gas engines and no automatic traction control, no Onstar crap.