Here are my two pennies on the Mayweather McGregor fight...
The impact on the sport: Boxing has a lot to lose. MMA has been growing fast and especially in the last few years (in large part due to McGregor and Rhonda Rousey) at a rate unprecedented in any sport. Boxing on the other hand has been in a decline, due to fight spoiling/avoiding politics, greedy promoters and lack of non-PPV TV coverage. If boxing's no 1 fighter can't handily put away a fighter with no boxing record, it further legitimizes MMA as the "go to" fight sport, and de-legitimizes boxing as a fighting sport. MMA on the other hand can only gain. No MMA fan will be put off by a McGregor loss as this is not McGregor's sport. Connor has an excuse not to win. Mayweather does not.
The fight itself: Who the fuck knows. It should be a cake walk for Mayweather. But again that's where he is at a disadvantage. If McGregor even goes the distance (which I think he can as long as his fitness holds up) then in a large part he wins. If he wins some rounds or even looks close to hurting him then again he wins the MMA v Boxing victory, since everyone knows in an MMA fight Mayweather doesn't just lose but gets seriously hurt.
As for the build up, and I'm very biased here, I think McGregor has been hilarious and Mayweather has come across as a moron (disclaimer: I'm a big Mayweather fan). Boxing fans, and also boxing media, have been petty in attempts to de-legitimatize this fight. It's pure jealousy based on a non boxing fighter generating more attention to the sport than any other fighter.
Obviously I want McGregor to win, if only to shut up all the whining boxing fans (when was the last time they didnt whine about a pay per view - I do it too!). In fact,I would be ecstatic if Connor gets frustrated and decides to roundhouse kick Mayweather, sparking him out, then turning to crowd and saying "Fuck the Mayweathers!". But I'll settle for a non-one sided 12 round fight.
Whatever the outcome I think it's the MMA fans that will lose in the end. With £100mill in the bank I don't think McGregor will fight again in boxing or MMA. In that point at least, I hope I am wrong.