A report from the Guardian, a British newspaper, reports that a deal could be already in progress.
If (or when) Real Madrid acquires Modric, there would simply be no room left for Kaka to get very much time on the pitch. Mesut Ozil plays the same position, which is why a Kaka deal may be all but inevitable.
With Real Madrid looking to unload Kaka, Manchester United seems like a logical destination. The team is trying to bolster its roster, and Manchester United is somewhat weak at midfield.
Man U most notably has weak attacking midfielders, which is why acquiring Kaka just makes so much sense. Despite being more than 30 years old, Kaka remains one of the best attacking midfielders in the world.
And while Kaka is a little past his prime at 30 years old, he's still in his youth compared to some of United's current midfielders like near-fossil Ryan Giggs.
Kaka is still an excellent ball-handler and would do a great job getting the ball to strikers Wayne Rooney and Robin van Percie. The two forwards are United's stars and main scorers, meaning Kaka's main role would be to play a sidekick role to the two of them.
Make no mistake about it, however. Kaka is still a viable offensive threat as well and won't settle for being just a sidekick. He still has a reputation as an outstanding attacking midfielder and would undoubtedly bolster Man U's scoring ability.
Acquiring Kaka would surely make Manchester United a more dangerous offensive team. After last year's disappointing end to the season, this is a move that Man U simply needs to make to once again dominate the English Premier League.