This is a great idea, but i dont think it would work as well this way. There are a few games out there that have single elimination tourneys thru matchmaking. For example, in FIFA 12 Ultimate team they have single elimination online tourneys with 4 rounds, hypothetically there are 16 teams but its basically normal matchmaking. In order for this to work you would need to have a set clan, like in Halo 2. Meaning that only the people who are in your clan will be allowed to enter the matchmaking tournament. For the first game of the tournament you would be in ROUND 1, meaning you would only be paired up with other clans in ROUND 1. If you win you will advance to round two, where you will only be paired up with teams in matchmaking who were in round 2 as well, this cycle continues all the way to the final championship match unless your defeated and then you will be reset to round one. NOW, I think this would work best if there is a set prize before entering the tournament so all teams will know what they are competing for, say... 25,000 CRT. Of course, it would be a good idea for 343 to have a set cap on how many championships a clan may earn in a month. They could also reduce the ammount of CRT for teams that have been winning more frequently than others. Personally, I think this would be much more competitive if it added a skill level like Halo 3, and stats for your clan... Wouldnt that be nice to have your clan in your service record with WIN/LOSS and Championships. And 343 could also incorporate "double xp" weekends and add more CRT to the championship match or feature items such as specialized armor, emblems etc. as prizes.
The diagram below give you a basic idea, but remember upon entering matchmaking you wont know who is in your tournament. Its basically just a simple matchmaking playlist that tracks wins and matches you up with other clans who are in the same round as you. This Diagram could be shown on the in the background of the CLAN PLAYLIST to help keep track of where you are in the tournament plus it gives it more of a tourney feel and a sense of accomplishment.
w
-------- you w
-------- you
-------- w
-------- you
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-------- -------- you w L
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-------- YOU vs. ? 4th round finalist SAME ON THIS SIDE
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1st 2nd 3rd Semi FINAL
round round round Finals
round
It would also be a neat feature if clans were customizable ex: logos, matching armor, clan tags ect. This would be just like the unlockable system in normal matchmaking, except exclusively for the clan playlist. And im tired of the set amount of emblems we are allowed to use in Halo, what would really be cool to have is something like the emblem editor in Call of Duty: Black Ops.
I really hope this idea gets to 343 because I think it would become extremely popular, spread the word.