By his own admission, Canelo only weighs between 178lbs to 180lbs between bouts, which is typical for a middleweight, since it’s normal for fighters to be slightly heavier out-of-competition than their rehydrated ring-weight.
So I’m pretty sure he’ll drop down a division or two immediately after he beats Sergey Kovalev, not just because of his obvious lack of size, but also due to fiscal reasons, since he clearly has far bigger fish to fry in the lower weight-classes than any of the fighters competing at 175lbs.