Last I heard, they were going to release AOTC and ROTS in the same year. That was a rumour, but I believe it, or at least that it is being seriously considered, to just get the PT out of the way. TPM wasn't a collossal failure, but I do believe it would be considered a minor one relative to the expectations they had. It made a profit theatrically, but only a small one. I don't think they ever expected it to do numbers like 1997, but I honestly think George believed that the 1999 box-office numbers were due to people genuinely liking it, and not because of hype, obligation, and all the other factors that drove people that hated the film to see it three times. A lot of fans said the same thing--if everyone hated it, how come it made so much money? On the surface, that would seem to make sense, people vote with their wallets. But this film is an exception to a lot of traditional release rules.
Without the hype, and having accepted that the film wasn't good and moved on, most people who saw the film in 1999 stayed home--almost all of them, it would seem. $671 million in 1999, in todays dollars, versus $43 million with inflated 3D prices or $30 million adjusted for normal prices. That's an estimated 84.8 million tickets in 1999 versus an estimated 5.5 million tickets in 2012. In other words, only about 15% of the people who saw it in theaters in 1999 came back this year. It pushed it into the $billion area, yes, but at the same time it took until 2012 reviews before the film officially became "rotten" at rottentomatoes. Neither accomplishments are too grand anyway, since the film was already close to the edge of both as it was.