It would be interesting, certainly, but unlikely. Without a united world, humanity wouldn't have had the numbers they needed to explore the galaxy as thoroughly as they have.No
Also, I think someone missed the whole point of Star Trek...
There are still other countries on Earth, but their rulers have little power in compairison to the United Earth and Federation politicians. Basically, the names of countries are more like areas and locations than competing states. The idea is a central world government making humanity's first steps into the galaxy, and individual nations cannot do that. If we can't unite Earth under one banner, then how can we form the Federation without heavy conflict between its worlds? I believe it was once mentioned that world government was one of the qualities the Federation looked for before you could join.
Wouldn't it be great if we all kept on fighting with eachother over pieces of land and different view points? Atleast now we can build colonies that will function however its founders would want.