Povetkin easy imo unless he has gone old overnight. Wilder doesn't like it when guys come forward and if he lets Povetkin get inside like a shot Chris Arreola even managed to do for certain periods of the fight (unfortunately Arreola had nothing behind his shots therefore Wilder could start twirling around like a muppet), then Wilder will be in for a long long night.
Having said that, Wilder will most likely fight a few more guys who are barely top 50 material.
I don't rate povetkin as high as many do. He went life and death in a toe to toe war with marco huck, which is frankly awful.
His footspeed isn't all that great although he does press the fight. I'm not high on wilder either but I wouldn't be surprised if povetkin made him look good tbh.