Note: Much larger version HERE, but you may need to open the image in a new tab to see it at full resolution.
Pangaea Ultima is a possible future supercontinent configuration that could occur in the next 250-million years "based on examination of past cycles of formation and breakup of supercontinents." It is NOT based on the current understanding of plate tectonics, which "are too imprecise to project that far into the future." So basically it's just a wild guess of what might be 250-million years from now, not that we'd ever need to worry about international borders at that time or anything else for that matter because the only even close to living thing left on earth will be a cute little robot pooping out compressed cubes of human garbage.
Thanks to n0nentity, who agrees 250-million years from now there probably won't even be an earth.