Floyd's most recent fight was in May against Miguel Cotto. It was an exciting bout, but one that saw Mayweather take more shots than we've seen him absorb in a long time. Some could argue this fight proved Floyd's toughness—which I've never doubted—while others would argue that he's slowing down a bit.
There could be some credence to the latter.
But Floyd Mayweather Jr is so skillful, even with a slight decline he's better than 95 percent of the fighters in the world. That said, he is 35 years old, and that is a major factor. If he doesn't fight this year—or at least very early in 2013—he'll be facing a year long lay-off when he returns.
That is a difficult hill to climb for a fighter in his mid-30s, and its compounded when the fighter is one who depends so much on his speed, agility and reflexes. It's been said, those three things are the first to fade as fighters age.
The fact Floyd Mayweather spent over two months in a jail cell doesn't help matters. Removing the moral aspect of the situation from this point, jail-life isn't exactly conducive to the professional well-being of a fighter like Mayweather.

He was separated from the comforts and traditional training regimen he's become accustomed to, and the toll this punishment can take on a person psychologically can't be understated. Who knows how Floyd's body and mind will respond after this ordeal and an extended lay-off?
As a result, it would be advisable for him to make a fight by December. Even if its a tuneup against an opponent that everyone knows he should handle easily, some in-ring action would be beneficial and enable him to shake off a bit of rust.

In 2013, Floyd Mayweather figures to be in the ring with a major opponent. It would be foolish to make that his first fight since the jail term and a nearly year-long lay-off.
Floyd Mayweather needs to be rust-free and in fighting shape, mentally and physically, before he takes on the likes of Manny Pacquiao, Sergio Martinez, Canelo Alvarez—or even Cornelius Bundrage.

If he waits until 2013 to have his tune-up fight, it still equates to a long lay-off, and he turns 36 in February. As great as Mayweather is, the magic is only going to be there for so long. The longer he puts off his ring return, the more vulnerable he'll be to a fall-off.
Hopefully, he and 50 Cent are working the phones to put something together. The jail term plus the inactivity could equal the end of 'Money' — at least as we know him now.