It is a new region. The games take place in Kalos, which takes inspiration from France.
Here's some more stuff about this:
At the beginning of the trailer, Pikachu is standing on top of the Eiffel Tower, and releasing a thunderbolt across the entire globe. This is significant because the game is taking place in a setting inspired by Europe, particularly France, and will experience a world wide release from this announcement at 11 am London time. - IGN thoroughly examining the details of the trailer.
Source: I watched the trailer.
