Well, the numbers are in, and the fight has indeed set a new record: HBO Pay-Per-View reported Wednesday that 2.15 million fans purchased the event, generating $120 million, both new records for any pay-per-view event.
Lennox Lewis-Mike Tyson in 2002 and Evander Holyfield-Tyson in 1997, each generated 1.99 million buys; so this is a pretty significant advance on those events. More impressively, Mayweather-De La Hoya destroyed the previous non-HW record. The previous non-heavyweight PPV record was 1.4 million buys, set by De La Hoya-Felix Trinidad in 1999.
A word about boxing being a dying sport. I think it's largely bullshit and a cliche to say that. As in mainstream news coverage, where bobble-headed pundits parrot anything vaguely interesting that they've heard--regardless of the truth behind the claim--uninformed sports pundits repeat the "boxing is dead" meme, because they don't know enough about the sport to say anything else.
In addition to the basic fact that setting a new PPV record is a good sign for boxing, the fight also indicates two more positive things about the sport: for one, it seems that casual fans, lacking an interesting HW scene, are willing to shift their attention to smaller fighters. In addition, it seems likely that Mayweather will carry considerable public recognition with him out of this fight, positioning him as a potential new mega-star of De La Hoya-esque proportions. Whatever you think about Floyd, that's good news in general for boxing.
And a word about the whole boxing vs. MMA thing: why do people assume that increased interest in one means decreased interest in the other? That's nonsense. There's no reason the two sports can't feed off of each other, as boxing fans purchase the occasional MMA event that catches their attention; and MMA, in turn, encourages new fans who enjoy professional fighting events, fans whose love of mixed martial arts may in turn lead them to watch boxing.
The reason why some recent boxing PPV events haven't sold isn't because boxing fans were buying MMA events instead. It's because the fights themselves were not worth buying. The real problem is promoters who think that it's a good idea for a fight like Maskaev vs. Rahman II to be on PPV in the first place.