Earth in 250 million years?

Today's astronomy picture of the day comes from Chris Scotese's Paleomap Project. I'm amused that the astronomers have used two geology images this week - I mean, it isn't as if astronomy is lacking in amazing images or anything. But I'm also curious what people think of the assumptions behind the future projection.

Here's the map projected only 50 million years into the future:



He projects that new subduction zones will form along the east coasts of North and South America, and in the central Indian Ocean. I'm guess that he's assuming that, when oceanic crust reaches a certain age, it will begin to subduct. I've heard that argued before, and it seems reasonable to me, but...

Why not subduction off the coast of Europe and western Africa? Is there anything about the North American side of the Atlantic that would make it more likely to form a new subduction zone? (And where's the youngest subduction zone on Earth now? And is there any evidence of how that subduction got started?)

Arm-waving and random speculation welcomed. Heck, encouraged. I've got a few more weeks before my Tectonics class starts talking about subduction zones, and they always seem to ask questions like "But how does subduction start? Huh?"

(Actually, Scotese asks some of these same questions on his "more info" page. And he speculates that the Caribbean and Scotia arcs will propagate; that's why there will be volcanoes on old New York and not on Ireland.)