I have never been a fan of trading Manny in the past, but if he won't block any trades, I think they need to look at options.
I just hope they do not trade him to an American League team.
They should be talking to the Dodgers, Cubs, Phillies, Mets, Brewers, and any other contender out West who is looking to load up. Maybe even Florida would be interested.
But when it comes down to trading him though, it all depends on what they can get. They need to get at least two top level prospects, preferably ready to play in the majors. When you look at how rarely a guy of Manny's caliber is available in trades (they may be more rare than Aces), and the fact that the team would then have 2 option years on him, he may bring back as much value as he ever would have.
Just to throw out the level of talent they should look to get back, in order to make it worth lowering the chances of winning this year, and not just taking the draft picks by letting him walk, they could offer him to the Dodgers for Matt Kemp, Johathan Broxton, and maybe a lower level prospect or two.