One theory posits that there will be a point when this trend shifts back in the opposite direction.

http://en.wikipedia.org/wiki/Pangaea_Ultima

According to the theory:

"About 150 million years from now, the Atlantic ocean is predicted to stop widening and begin to shrink because a bit of the Atlantic Ocean mid-ridge will have been subducted. In this scenario, a mid-ocean ridge between South America and Africa will probably be subducted first, the Atlantic Ocean is predicted to have narrowed as a result of subduction beneath the Americas. The Indian Ocean is also predicted to be smaller due to northward subduction of oceanic crust into the Central Indian trench. North and South America may be pushed back southeast, and southern Africa would almost hit equator and have reached the Northern hemisphere. Australia may join back to Antarctica, meeting the South Pole.

When the last bit of the Mid-Atlantic spreading ridge is subducted beneath the Americas, the Atlantic Ocean is predicted to rapidly close with a new Pangaea forming.

At 250 million years in the future, the Atlantic and Indian oceans are predicted to have closed. North America is predicted to have already collided with Africa, but be in a more southerly position than where it rifted. South America is predicted to be wrapped around the southern tip of Africa, with Patagonia in contact with Indonesia, enclosing a remnant of the Indian Ocean (called the Indo-Atlantic Ocean). Antarctica would then once again be at the South Pole and the Pacific will have grown wider, encircling half the Earth."

Contrary theories that posit that there will be no shrinking of the atlantic:

http://en.wikipedia.org/wiki/Amasia_(continent) http://en.wikipedia.org/wiki/Novopangea