Somehow my earlier posts about speculative future continental drift neglected the great Oct. 20, 2007, article at NewScientist.com, "Pangea, the comeback".
Most of these projections assume that, over 300 million years or so, Australia (and possibly Antarctica) will fly across the Pacific Ocean and collide with western North America. Then, the Americas will mash together and collide with the eastern edge of Afro-Eurasia. The exception is Christopher Scotese's Pangaea Proxima, which has the Atlantic Ocean stop widening and begin to shrink away.
These are all just speculation, of course, and apt fodder for fantasy. Grognard James Maliszewski, considering setting his old-school RPG in a hypothetical future Pangea, pointed out that the map of the Mystara campaign setting was based on the continents of the Jurassic. Commenter Malcadon points out the similarity between Robert E. Howard's Hyborian age and the Afro-Eurasia of 50 million years from now.
Dougal Dixon, an author of "The Future is Wild", has another similar work: After Man: A Zoology of the Future.
Offensive redirected link removed for the Hyborian Age. Try Wikipedia here or here.