Banning signature campaigns would have big consequences to the forum and also to the bitcoin adoption as well. Signature campaign have created a micro economy for new bitcoin users who don't money to buy bitcoins. Signature campaigns is their only means to acquire bitcoins.

I predict only nerds and geeks would remains and noobs would come occasionally if bitcoin talk disable signature campaigns. Bitcointalk would be replace as number one bitcoin forum in 1-2 years. Theymos would lose his monopoly. This would give a chance for bitcoin classic to win.

I suggest a mandatory tax to every signature campaigns. I suggest for every btc spent on signature campaigns 10% would be given to the mods.