Actually, there was nothing hasty about that at all. It has been stated, in many interviews with Jake Solomon (the lead designer) of XCOM: EU, that the game has been in production for 4 years at least, largely due to Jake's desire to create it. So it was being made for 3.5 years (or starting from 2008/2009 which is way before the XCOM FPS announcement) and only this year was its existance finally revealed.The poor response to footage of 2K Marin's 1950s XCom FPS reboot seems to have prompted the hasty release of a more traditional XCom game from Firaxis.
Please do a bit better research before writing something like this.