I guess the future lasts forever so it doesn't matter when it starts.
But as far as 2017 and 2018 are concerned, I think I would be more excited about having Mahomes joining the team, then an unknown future drafted QB. Not because Mahomes is automatically better than someone we would draft next year. Just simply the fact that a 2018 drafted QB likely won't be available prior to 2019. There are other ways to fill the CB spot than with a #1 draft pick.