Currently only 5 players from each region is able to go. In pretty much any other sport you can have multiple line-ups or multiple players for the same position and just switch them out in-between each break.
Personally, I'd prefer to see maybe 10-15 players from each region go (5 from a fan vote, and 5-10 from analyst votes who can pick out the most skilled players). Since the teams compete against each all-star team from the opposing fire/ice team, it'd be enough for 3 lineups worth of players, the problem comes with some of the fun gamemodes that come up and such, but I'm sure something could be figured out amongst the players to decide who does which event and such.