When MLS started in 1996, they made an effort to insure than no MLS team was sharing their stadium with a baseball team. Several USL teams have baseball/soccer stadium sharing but until this season, no MLS team did.
When the Montreal Expos moved to RFK stadium in DC the new Washington Nationals, DC United and RFK stadium people all said they had a plan to insure the room mates would get along. Recently, it was reported that the pitch at RFK was lopsided. Now, it seems there are even more problems with the arrangements.
Who will be the first to move? Will RFK stadium end up with no tenants once all the dust is settled? My guess is that DC United will bite the bullet until the Nationals move out and the have the place all to themselves again.