The only ones able to purchase tickets to the 2013 con were the ones that were registered to buy the 2012 tickets
. I don't know if an advanced warning was given to the general population since they were not able to purchase tickets, I'm sure the SDCC comity didn't want those email, phone calls and threats. There might be a chance for future ticket sales later but even then, to whom are they going to sell the remaining few?. Exhibitors, professionals and press passed are still not for sale, those will be sold next year.