I think this will continue to divide the community for a long time no matter what happens, MK won't really be banned or unbanned at some point, I think the two will have a strange coexistence for some time. I see this as happening in the following ways
1. SBR votes no ban, some places like texas and socal ban him anyway, some others may follow suit but the majority won't
2. SBR votes ban, places like europe and atlantic north will not ban meta knight anyway.
A) in either of the above cases, some regions will be intermingled and pro and anti ban tournaments will take place simultaneously, with one proving to be more successful than the other. eventually the other ceases to exist, rendering the SBR's judgement totally unimportant in the end.
B) MLG picks up brawl again in 2010 and uses the SBR's recommended rules, this is now official and major so most tournaments will follow because no one wants a scrub community that isn't prepared for a character that is totally legal at the highest level of play
C) brawl dies a horrible gruesome death and we all go back to playing melee like we should have been from the start.