Apparently he is willing to try:

http://www.mixedmartialarts.com/news/262081/Pacquiao-Im-willing-to-try-MMA/

"During a recent press conference, BoxingScene.com's Bill Emes and Michael Marley cornered Manny Pacquiao on the subject of Mixed Martial Arts. Pacquiao said he watched MMA and UFC, but said it was "too brutal" when asked for his thoughts on the sport.

When asked if he would ever consider trying his hand at Mixed Martial Arts, Pacquiao replied to BoxingScene - "I want to, but they [promters and management] don't want me to fight."

He said if promoter Bob Arum of Top Rank and adviser Michael Koncz said it was okay, he would consider entering the cage. Michael Koncz cut in at that point and told Pacquiao - "you know that you could do what you want."

It's hard to tell if Pacquiao was serious or just joking around."

There seem to be some rumors about him possibly going up against Jose Aldo.

If he is interested for financial reasons, the UFC (or whoever) will need to stump up some cash to get him to cross over. The guy makes 8 figured sums these days for boxing matches.

Could happen, but it could just be a ruse to bait Mayweather in to getting in the ring with Manny "Look Floyd, Manny is leaving boxing for MMA! We better get a deal done soon or else we'll have to met him in the Octagon!".

After the Toney farce, I don't know if the UFC or any other MMA orginization would be willing to take on any more boxers. Unless they were like Kermit Cintron, a pro boxer who wrestled in high school and was apparently offered wrestling scholarships by two universities in the USA.