Ricky Burns and Miguel Vazquez won't be fighting on March 16 to unify the WBO and IBF lightweight titles, as the fight has been officially "postponed," which comes as no surprise to anyone who has been following the news. There was already significant speculation that the fight wasn't going to happen.
As of now, the March 16 bill at Wembley Arena has not been called off in full, but at this point, all the show contains is Nathan Cleverly vs Robin Krasniqi and a bunch of fighters lined up against TBA opponents, which doesn't bode well for having anything interesting on the undercard given there are 13 days until the show.
In short, the show being canceled is probably expected at this point. Warren announced Burns-Vazquez, Cleverly-Krasniqi, Groves-Ndiaye, and Dereck Chisora's return, and all he's able to deliver now is Cleverly-Krasniqi. Groves dropped out and will be signing with Matchroom, and Chisora doesn't even have a license.
The official reason appears to be that Vazquez is injured, which I don't think anyone is buying. Vazquez already said that there was no finalized contract for the fight, a rumor that had gone around well before he made that statement, and Warren calling that talk a "rumor" appears to be typical promoterspeak, saving some face, which is fine.
Burns' manager Alex Morrison says that their side is very unhappy with this development, as Ricky has now not fought since September, after losing a date in December and now this one.