It has come to light on the official XCOM Twitter page that XCOM 2 has now been delayed. The developers were originally aiming for a November 2015 release window but this tweet and this news post from the official website reveals that the game has had to be pushed back to February 2016.
The aforementioned news post and conversations with the Twitter account suggest that this delay was decided upon in order to ensure an extra level of quality for the sequel. In the developers’ own words “We just need a little more time to make it the best possible game.”
XCOM 2 will be available worldwide for PC on February 5th 2016.