But ultimately the point is moot. FC is clearly a reboot of the X-men franchise, and thus set to be a new trilogy.
You're half right. First Class is meant to be the start of a new trilogy, but it is not meant to be a rebooting of the X-Men film franchise. It is intended - according to comments from Singer and others involved with the film - to be a prequel to the first X-Men film and its sequels, inconsistencies notwithstanding.