Not gonna to happen. At least on the Marlins end.
The Braves likely wouldn't give up a home game or series at Turner Field, which regularly draws much more than Disney's Ballpark can hold. But, perhaps, the Florida Marlins or Tampa Bay would consider moving a series to Disney in lieu of games at their sparsely populated parks.
There is no way that the team will take away a regular season game from the South Florida fans. It's a little hard to justify for the public to chip in money towards a new stadium when you are screwing the season ticket holders out of a game. No matter how small that number may be.