Bungie has done a lot with and for MLG, but I've never seen anyone from Bungie say MLG is the future for its games. MLG is just part of their much larger community. With the amount of customizing options that were available in Halo, MLG definitely benefited. I'm not seeing this for Destiny. I worked for MLG during the '08 season on the Video on Demand team and I remember Bungie letting MLG do an exhibition game with the never before seen Halo 3 map "Blackout". I think it was Luke, but I was pretty busy and didn't have time to go all fanboy on whoever it was.

There have been Halo multiplayer tournaments and gaming championships

Not really while i could see them supporting Roosterteeth, MLG would have wanted endorsements getting paid. Bungie i am sure would pay people but only if they are Testing or Developing the game. Or if there was some payoff or benefit for fans all over. Bungie does not strike me as people who do things out of the fact to make just money. While the goal is to allow people to play there games it just helps fund future projects and people's Salaries so they can continue to do there first love that is passion about the game industry not to mention work on awsome games.. That kind of arrangement would be more like how Microsoft or Sony operates only seeing the $$ in the end not to mention profit.

I'd like to think that Bungie would be very happy that people would want to make a living playing and hosting events using their games.