No, The Avengers should stay in theaters as long as it's making money. Disney isn't going to pull it for a while yet. The discs will come out on September 25th regardless of whether it closes in June or late August. I still think Marvel ought to try for an IMAX re-release in August to see if they can't up the totals and give people one last burst of fun before the Fall grind commences.
Whenever there is an opportunity, like a new Avengers film coming out or an anniversary, Disney should re-issue The Avengers the same way other studios put their films back in theaters. Each time it's bound to earn millions more, so the total take will rise. Eventually TA could equal or topple Cameron's films. And who knows how much money The Avengers 2 will rake in.