I'm still not sure about your idea...it just seems to boil down to reducing the incentives while keeping the price high, so of course there is some point where you can adjust that mixture to where you will only sell the number of tickets available.

I agree with the argument that the keynote attracts some people that otherwise don't care (though the WWDC is always super crowded post-keynote), but considering the other conferences that have this problem, the volume of people buying tickets, and the volume of people upset with the process that denied them tickets, I'm not convinced that going keynote-less would be sufficient to erase the issues with ticket buying. And that's really the only knob you have except for raising prices, which certainly does your attendee demographics no favors.

I also really have to agree with saurik that, even if you can reduce demand to have tickets sell out in, say, an hour, simple distractions that morning (kids, forgotten meetings, car problems) still mean you miss it, which will again heavily skew your demographics to the set of people glued to twitter who would never have missed the 30-minute, 15-minute, and 5-minute warnings of impending ticket sales. Some of those people are going to indeed be the true fans, but many will just be seeing those by virtue of attributes that bring no advantage to the conference, and may limit its reach. It takes all types :)