Ex-UFC Star Kenny Florian -- Boxing Is Finished ... After Floyd/Manny Mega-Fight

Ex-UFC fighter Kenny Florian says boxing's days are numbered ... and the number is 64 ... 'cause that's how many days are left until the Mayweather/Pacquiao showdown, which Florian tells TMZ Sports is the sport's last hurrah.

Florian -- who was a UFC badass from '05 to '12 -- was out at The Grove in L.A. when we asked him about the future of the other sport where guys break each other's faces.

Check out the clip -- Kenny says after Mayweather and Manny dance ... the music is going to stop ... because all of the big stars in combat sports are over in the UFC ... and NOT in pro boxing.

One man who disagrees -- Mark Wahlberg who told us M vs. P is just the beginning of boxing renaissance.