Well Bilbo, whilst I do see your point of view I can also see flaws in the theory.

I feel the primary issue is their ages. Calzaghe is a realatively "young" 35, Roy is an aged 39 and Hopkins a 43 year old beginning to show his age.

Imagine see three situations.Here's my view of each as a fan of each possible victor:

Roy does indeed "return" and beat Hopkins and Calzaghe. It's seen as a great feat and Roy is hailed as Top 5 ATG's for his new boxing abilities far from his prime.

Hopkins beats both guys, his CV expands and he too is enshrined for beating the much younger Calzaghe and avenging agaiunst a far from Prime Roy Jones who was avoiding him anyway.

Calzaghe wins. Seen as decent wins and his reputation as a big fish in a small pond is diminished. However he doesn't receive full credit because he had such an advatage in age particularily in terms of Roy.

the sitaution has pros and cons for all parties. Money is an obvious pro. However, I see this as the only reason Calzaghe would fight Roy. In my mind Roy has done little to warrant a shot at the top guys and is merelky angling for more money and using his name to get in fights.
I would forgive Hopkins for fighting him as he obviously wants his revenge.

So after all that rambling: After Joe and Bernard fight I can see Roy fight either.
However If Joe fight Roy, it's blatantly for money, nothing to promote legacy nor record and I see it as a blatant money spinner of which is of no benefit to anyone in boxing apart from the participants.