Do I care about what happens next on Pandora? No, not at all, not even a little bit.
Do I want to see the next film in the series? Only if it can surpass the experience of watching the original. Immersion was the only thing going in the first film for me. It was truly, epically impressive on that front, but that was all it had to offer, AFAIC.
That said, improving on the experience of the original could mean bringing something new to the table in any area. It doesn't just have to mean improving the immersive aspects of the experience. For example, if for whatever reason the "immersive arts" have plateaued, then improving on the original would mean improving in at least some of the other areas, such as story. There is plenty of room to do that.
Cameron has told great stories before, in T1 and
Aliens, IMO in
The Abyss, and in
True Lies, though it has been a while, over 20 years. I haven't seen all the films he's written; I missed
Piranha II and
Strange Days, and I haven't had the opportunity to see
Xenogenesis. However,
Titanic was a colossal bore to me. He obviously knew what he was doing there in making a blockbuster, though, just as he did in
Avatar, so good on him, but the sort of thing as
Titanic just doesn't interest me. Rewatching
Avatar on the small screen has never been engaging, and once was enough in the theater.