Avatar was released in 2009 to receive huge acclaim, and it is odd that one of the biggest films of the year has not had a sequel by this time.  In comparison, Iron Man was released in 2008, and there have been three individual sequels and two Avengers films, not to mention Iron Man's presence in Captain America: Civil War coming in 2016. Considering that Avatar was intended to have sequels, fans are constantly asking about the delay for Avatar 2, Avatar 3, and Avatar 4.  This is what is known about the possible release dates of all three sequels of the Avatar series.

The delay for the sequels can probably be summed up in two words: James Cameron.  Okay, that could technically be one word, but this is the filmmaker who directed Titanic, the former biggest film of all time in 1997, and then only produced films for those twelve years, but finally had a chance to release his dream project in 2009. 

In other words, James Cameron is a filmmaker who takes his time.  Considering the hits that he has been able to put out like Aliens, The Abyss, Terminator 2, True Lies, there is a growing gap in the amount of time he puts out a film.  He is not like other directors that can juggle two moderate hits a year, but he does them big and is famous for going over budget. 

In short, Cameron takes time before he pays off, and Ubergizmo states that Cameron revealed that he is in an ongoing process of writing the technical development and stages as well as the infrastructure for the sequels, but he is poised to begin shooting at the first of the year. 

Yes, that is a delay, as Avatar 2 won't be out on the big screen until Christmas 2017, at the earliest.  The original plan of release was Avatar 2 in 2016, Avatar 3 in 2017, and Avatar 4 in 2018.  Yes, you heard it right.  Unlike other franchises that attempt the "tacked-on trilogy" with two films in the franchise with an expanded storyline, Cameron wants a quartet of Avatar films.  He plans to direct all three of them at the same time, a lot like Peter Jackson did the first Lord of the Rings and Hobbit trilogy.

So what will the next Avatar films be about?  Well, considering that the Na'vi kicked Earth out of their planet in the first film, it would make sense if Earth just remobilized another army and just came back for their unobtainium.  From there, it could become a serious galactic war between Earth and Pandora.

That would be the main plot as there could be some side there will be a lot of secondary plots as Jake and Neytiri will develop their relationship.  There have been a lot of talks that the war between the Na'vi and the humans will separate them, for good reasons.  After all, Jake is originally a human.  As for Stephen Lang's character, he could be the grand villain of the next three movies, but it is likely that his character could go through a transformation.  That is, he might end up joining the Na'vi in the fight for their land.

Look for Avatar 2 by Christmas 2017, followed by Avatar 3 in Christmas 2018, concluding with Avatar 4 in Christmas 2019.