That said, I don't think (2) can be equivalent to (1). While (1) expresses cetainty, (2) only expresses possibility.
I agree with Gustavo and would like to point out, in case it isn't already clear to you, Ruifeng, that the coordinate structures you are using have a conditional meaning. It's the difference between "If you watch TV all day, you will be a couch potato" and "If you watch TV all day, you can be a couch potato." The second sentence, then, states that one will have the opportunity to be a couch potato if one watches TV all day, whereas the first states that watching TV all day will make one a couch potato.