It already happened the first time. Legalisation was in the top 3 Ideas, but Obama breifly passed it with "people say legalise pot to help to economy or something - I don't think thats a good idea" He could have at least looked at it seriously. EDIT: http://www.change.org/ideas/view/legalize_the_medicinal_and_recreational_use_of_marijuana
with a president like obamna, i dont think marijuana will be legal anytime soon. i mean, he hasnt done jack shit since he became president.
I don't think it'll be legalized but it most likely will be descriminalized. California needs 650,000 signatures by January for it to be legalized.