For many years, the US and European markets have been mirror images when it comes to transmission choices. Both markets have been split roughly 90/10 percent with the American market favoring automatics and the Europeans (and most of the rest of the world) preferring to shift for themselves. Overseas drivers have gone for manuals for the increased efficiency at least in part because of the much higher gas prices there.
Now with the proliferation of advanced power-trains, particularly hybrids, getting them to operate smoothly with a stick-shift is getting problematic. As a result, many of these cars are only available with automatics or CVTs that can be programmed to manage the shifts to work effectively with the rest of the power-train. The other main driving force is increased congestion in urban areas, that can make rowing a gearbox a rather unpleasant experience.
As the world migrates to primarily electrically driven vehicles like the Chevy Volt and Ford HySeries Edge, that will drive the final nail in the coffin of the shift-it-yourself gearbox. Electric motors offer essentially a flat torque curve from zero rpm up to their maximum speed. Electric vehicles generally have a single or two speed transmission, plus a reverse gear, because that is all they need.