ufc 200 is months away, then add the break he will take for the next fight.... it will be almost a year by then...He won the title in december, 3 months have passed, and you are already talking about vacating. C'mon. He's been fighting pretty regularly, it's not like he fights once a year, and only at WW.
If he loses he might go back to 145 and defend before the end of the year.