As has been previously reported, only Timothy Bradley and Ruslan Provodnikov (and it looks like only Timothy Bradley, really) are possible April 12 opponents for Manny Pacquiao, when the Filipino icon returns to the ring in Las Vegas on HBO pay-per-view.
Bob Arum shot down the ideas of Yuriorkis Gamboa or Robert Guerrero being opponents for Manny. From Ronnie Nathanielsz:
Arum told BoxingScene.com/Manila Standard that Gamboa's name didn't even come up in his discussions with Pacquiao's adviser Michael Koncz, while he dismissed trainer Freddie Roach's statement that Guerrero would be worth fighting because an impressive win by Pacquiao, would put him closer to a shot against Floyd Mayweather Jr. as "nonsense."
Gamboa (23-0, 16 KO) is still really a featherweight masquerading as a lightweight, and a jump to welterweight to fight Pacquiao is indeed crazy, but I wouldn't be terribly shocked if by the end of 2014, that fight becomes viable -- or, at least, "viable."
Guerrero (31-2-1, 18 KO) is still a Golden Boy fighter, and furthermore is currently sidelined trying to break free from his contract with them. The idea that he could be guaranteed for April 12 is silly right now -- it's just not in the cards.
It still appears as though Pacquiao (55-5-2, 38 KO) will face Bradley (31-0, 12 KO) in a rematch of their controversial 2012 bout. Provodnikov's name has been attached, but he's a Wild Card fighter and that's probably a tougher sell anyway.