To me is almost impossible to get DLC content. And when I finally get my ps3 in the last december. DA was one of the games I was wating to play. But Bioware eventually started to release a lot of DLC. So I decided to wait for some kind of rereleace to buy it, just like I did with RE 5. 
But E3 is coming, a rumor about a new DA release is being hear, and no DA:O+DLC.
Do you think should I get it, or should I wait a little more? There wll be any rerelease?

I would just get the game if I were you. DLC is great and I even downloaded some for my PC version but it's not needed for you to enjoy the game. The game itself is massive enough without it.
 
Are you planning on getting it for your PS3 or PC?

Well, they did say they had a year (or was it two years?) of DLC in the pipe. However, most of it is kind of overpriced (But really, the only DLC that is mandatory is Shale, and he might still come free with a new copy of the game) and a hypothetical "Game of the Year Edition" wouldn't come out until this holiday at the very earliest. I think you are good with just purchasing it now.