Come 2015, nobody will remember it... And I will bet with you on that.
This conversation is mind-bogglingly stupid. Of course people will remember Avatar in 3 years. People still remember Cameron's last blockbuster, Titanic. That came out 14 years ago and has a similarly thin story and "just okay" acting.
Top 10 Highest Grossing Films in History (all of which would make, or have made, extremely popular attractions):
1 Avatar $2,782,275,172 2009 [# 1]
2 Titanic $1,843,201,268 1997 [# 2]
3 Harry Potter and the Deathly Hallows – Part 2 $1,328,111,219 2011 [# 3]
4 Transformers: Dark of the Moon $1,123,746,996 2011 [# 4]
5 The Lord of the Rings: The Return of the King $1,119,929,521 2003 [# 5]
6 Pirates of the Caribbean: Dead Man's Chest $1,066,179,725 2006 [# 6]
7 Toy Story 3 $1,063,171,911 2010 [# 7]
8 Pirates of the Caribbean: On Stranger Tides $1,043,871,802 2011 [# 8]
9 Alice in Wonderland $1,024,299,904 2010 [# 9]
10 Star Wars Episode I: The Phantom Menace $1,019,093,635 1999 [# 10]