The bottomline of course of this match is about the money. But yes it is true, McGregor and Pacquiao will give a better fight in the ring as they will really give what they've got. Unlike Mayweather, which is always playing safe, counting technicals and others. And if this will happen, I think boxing fans will still watch this fight with enthusiasm.
I believe that Manny could give an exciting play but I doubt how McGregor could give. McGregor is old already and he even doesn't show the best fights for many years and he asks Manny for a fight? I don't think that Manny will give him a fight but rather to pick one that it looks exciting for him.
I also bet that this will never happen...