This has potential. I personally disagree with a couple things though.
First off this would totally eradicate the casual clan. What if me and my friends want to form a group to pub? Not a dedicated clan v clan group but just some friends who enjoy a common identity? Leave the clan tag for everyone but make some small distinguishable graphic to tell players whether or not a clan is casual or competitive.
Secondly I don't think this would be as easy to implement as you think. Sure it might just take one decent sized update, but so did the whole reworking of the freaking XBL dashboard. They all seem small from the receiving end but I'm pretty sure they cannot just decide to include a whole separate service and matchmaking system just like that. Now I'm no programmer or designer but I think if this is used then start it out small, then maybe make updates and expansions to the base service. This could help to make it stable and manageable from the beginning. If there is one thing we have hopefully all learned from MW2 it's that pushing content over stability and balance resolves in nasty ways...
I support the idea but think it needs a little refining. Let me know if I am missing anything in your posts. I must admit I didn't read all nine pages of this.
