At 42 years old, Pacquiao still has a long lineup. He should fight at least 2 times a year. But with that age and I think I read elsewhere that after 2-3 fights he will now hang his gloves, (the first count against Broner, 2nd Thurman so 3rd last?). He is still in his shape so only he knows when to retire.
As long as i have being a boxing fan i remember Manny Paquiao taking long breaks and goes to semi retirement and the only reason he said he is returning is to raise money as he needs money for charity and a Conor McGregor fight could be a retirement fight as he could earn over $100 millions and it could be his biggest payment in his boxing career and hopefully he spends them wisely and not return again.
Spending it wisely shouldn't be a question for a like of Manny Pacquaio.
But for whatever the purpose why he will step on the ring again, Manny knows well when to stop. It's been a talk before that he will retire but Pacquaio responds that he can still fight.
I'm not considering a fight against McGregor as a professional match. It more of an exhibition match for me.