I expect Mayweather to dope again like he did for the Pacquiao fight. That said boxing skills will destroy MMA.
That's the reasonable thing to say, and I believe it. But what gives McGregor a shot is the fact that he is an amateur in the world of professional boxing. Mayweather can easily prepare to meet another professional because professionals in any sphere of endeavor are largely predictable. Amateurs are unorthodox; you cannot as easily anticipate what they are going to do and be as well prepared. The one fighter who gave Mayweather trouble, and beat him in my view, was Marcos Maidana, who threw punches from odd angles. Mayweather was not prepared for Maidana, and without help from the judges, that would have been his first loss. This may be the case with Mcgregor, who certainly has the punch to hurt Floyd if he connects.