I have to say the success of AVATAR baffles me a bit. Now it's a fine movie, but if you have seen lots of movies, the plot is very 'been there / done that', absically Dances with wolves, except the good guys win. I always tell people that BO success is based mainly on awareness, mass market appeal, and hype, and that quality is only a modifier of that. I guess the 'new 3D' plus the 'first James Cameron movie since Titanic' caused the awareness and hype to be phenomenal and the DWW storyline has universal mass market appeal. However I still find it hard to see why this movie is now the #1 grossing movie of all time.
Anyway I'm really glad to see that CA:TFA is doing so well on blu-ray/dvd. I too hope that this means we'll hear a sequel announcement soon. I love the movie and find that it's one of the most rewatchable movies in ages (wearing out my blu-ray). So I'm eager to see more of CAP's adventures after THE AVENGERS.
That said I wonder if THOR is actually underperforming on blu-ray/dvd sales? It may be that a significant contributer to THOR doing so well at the BO was women and maybe they don't buy dvd's as much (although the sales for Twilight would disagree with this).