Oh wait... we can choose to see them in 3D theaters or not? We don't HAVE to give him and 20th Century Fox our money if we don't want to? Oh... nevermind. Anyway, starting in winter 2012, Lucas will be releasing one Star Wars film per year into theaters with a 3D conversion, starting with The Phantom Menace and ending with Return of the Jedi in 2017.
As usual, this is less about Lucas' greed (he's already worth $3 billion, and he's pledged to give half his estate to charity upon his death) and more about him using his Star Wars films to play around with new technology, in this case perfecting the much-maligned art of 3D conversion. Finding time to see all six of them in a theater at one time would be a bit much, but revisiting them in 3D at one per year during the dead-zone of January/February is perfectly fine. First of all, it will have been 15 years since these things were in theaters in any form, so it's not like he's milking the cow every couple years (nearly 14 years after the Special Edition releases in 1997, Star Wars: Special Edition still has the second-biggest January opening in history).
Second of all -- and this is a biggie to those who accuse Lucas of being purely out for financial gain -- Lucas was among those who signed 'The Giving Pledge' amongst billionaires to give half their estates to charity. So a ticket for The Phantom Menace 3D is a partially charitable donation to whatever foundation Lucas bestows his billions (probably education-related).