as money making gimmicks go, its making a lot of money.
Not just Avatar, but Alice in Wonderland, pretty much any animated film, and the horror films that have done it have all seen healthy business. Not only that, but they've seen healthy international business. The last (and kinda shite) Final Destination movie was the highest grossing one in the series.
I know there's always going to be a movie industry. But I can't help but think that there's going to be some sort of major collapse in the future where all those massively expensive tentpole movies become unprofitable because people get tired of spending lots of money to go see shit in a shitty theatrical experience, and now they can spend even more money to see shit in 3D. I keep thinking people are going to wise up, but obviously I'm very wrong as of currently.