I know that I am not the only person that wishes to use a specific character on attack and want to play a different character on defense sometimes. I would put this is casual, but not competitive. This would allow for players to change their play-style mid-game, and bring a twist into the really long games. Attacking? Use Jett. Defending? use Cypher. I think adding a cap to the amount of people each team can switch, say 3, would also make it to where it isn't such a game changer too. While I believe there will eventually be more characters to choose from, I think this half-time switch will be even better.