I dont know what people are talking about. The PT is widely regarded to be abysmal...and rightfully so. Avatar on the other hand, is not. Uninspired and cliche? Definitely, but it wasn't considered a horrible movie (even though people on the internet love to be overdramatic about it whenever its brought up but remember the rest of the world doesnt really care about box office numbers like this so there isnt so much animosity towards Avatar)
Although ROTS was a step in the right direction, it was too little too late. Star Wars is obviously a bigger franchise overall than Avatar. No comparison. But it would be ridiculous to assume its going to break records when there were three films that were far from stellar (no pun intended)....and considering how disappointing the prequels were, they did VERY well at the box office regardless. I'm not sure any other trilogy could've had the same box office results with three disappointing films -- so obviously the star wars franchsie is far from dead. However, this one is just not going to be a record breaker. It'll still make big money for sure but Avatar 2 has this beat EASILY. I think episode 8 is going to break all sorts of records if episode 7 is recieved well.