While I am a fan of Conor's, and would like to see this fight... let's not fool ourselves here... he is NOT a boxer, he is an MMA fighter. There is obviously carry over, but Floyd Mayweather is a brilliant boxer who is going to toy with McGregor in the ring.
Does Conor have a punchers chance? Sure.. but Floyd does not stand and trade, he is slick, and he punishes fighters for every missed shot... his movement is exceptional. The chances he catches Floyd is very, very, very unlikely.
Could Floyd have suddenly gotten old, or not take the fight seriously? Sure... which would matter if the guy he was facing was named Canelo or Cotto... but even an old, shopworn, disinterest version of Mayweather is going to make Conor look like an amateur boxer.
Could Conor pull off a "Buster Douglas'? Well, not really comparable. Conor McGregor has never fought a professional boxer, not one ranked in the top 100, top 10.. and he is going to be facing the P4P best fighter of the last 10 years... Buster Douglas was an under-rated boxer, who beat some of the best HW's of his time, he was a big enough to hold off Tyson from bully him, and his jab was probably the best in the division at the time.
Conor would crush Floyd in seconds in an MMA fight.. or even a modified rules fight.. if kicks were allowed... but that is not what is being discussed.. it is not a knock on the Irishman.. I give him all the credit in the world... but when it is all said and done... Floyd will toy with Conor...