He would have lost eventually because his pace/workrate was his main weapon that won him a lot of fights and that inevitably declines with age.

Lose 20% of your commitment and he might not be as super fit stamina wise as he usually was and could find himself on the wrong side of a decision. But I dont think a top form Calzaghe loses to anyone currently around no, he just racks up too many points.

I think he quit at the right time. I think the fact he got put on his ass in the 1st round of his last 2 fights was a wake up call. Maybe showed a bit of complacency on his part. Maybe wasnt absolutely 100% focused on fighting. Maybe his skills/speed were starting to decline.

And fwiw I believe only those with the heaviest Hopkins/Reid tinted glasses could say he lost those fights. Hopkins draw at best and Reid took too many rounds off to get a points decision.