Yes it is possible. The plates of the earths plate tectonic system are in relative motion that ultimately depends on circulation of platic rock in the deep earth. There is no reason why the crust that forms the continents could not again come together. This does not mean it will happen...but it could... many, many hundreds of millions of years from now.

Since the plates covering the Earth are constantly moving there will always be a possibility of forming a large super-continent like Pangaea.Within Earth's geologic history there has actually been more than one super-continent although it was over a billion years ago. Here is a good website to get some information on tectonics.

It's highly unlikely. Pangaea was just one configuration of the continents in Earth's history. They have before and since moved into new configurations.

It's happening right now. North America is colliding with Eurasia both on the east and the west as the two continents drift north to close the Arctic; Africa is slamming into Europe, and Australia is in the process of ramming into southeast Asia. South America and Antarctica will be independent, but there were pieces of Pangaea that were separate as well (including much of what is now China). Nor was Pangaea the first super continent itself; there was another called Rodinia about 700 million years ago that broke up and then reassembled to become Pangaea. There is even some evidence that Rodinia wasn't the first, either.