OP must not be familiar with the work of Floyd Mayweather. Floyd will knock him out in under 8 rds if this fight happens,and he'll make him look ridiculous in the process you can take it to the bank.
There's such a staggering difference in skill levels here it's almost difficult for me to explain - Floyd will make him look like an amateur.
The facts of the matter are there are much lesser boxers than Floyd who would murdalize McGreggor in the ring. Canelo would make short work of him.
I feel like McGregor would tire himself out in the first few rounds, probably missing a ton of punches, then Floyd would just utterly dominate him after that with a chance of KO rising exponentially every round after the 3rd.