Hopkins would clearly win four rounds, Canelo would clearly win four, and the other four would be very close. This would result in 116-112 scorecards for Canelo.
Hopkins was a tricky, crafty guy who knew every trick in the book. He's an easy fight for nobody. I think he'd have trouble with Canelo though. Canelo's fast hands, counter punching and extreme power are a lot to deal with. The younger version of Canelo loses. This version of Canelo is smarter and fights more disciplined and economical.
Seriously though, pretty good matchup. Canelo is strong with a good chin, but Hopkins was a really good middleweight. I'd make prime BHop slight favorite on points.
Hopkins split decision. People forget how good Hopkins was at slowing down the pace of fights and fighting negetively.