It's actually a pretty tricky situation. If enough states ban it, then the FDA would probably just follow suit. If the FDA bans it, well, the states will follow suit. It is a bitter rivalry between states and the federal government. Technically, the government is not supposed to be able to dictate what the states do in that respect, unless it is specifically unconstitutional. Take medical ......... for example, states can legalize it, authorize dispensaries, regulate and oversee it, but the federal government will sometimes just swoop in and raid the place. Against federal law, yet technically, the fed doesn't have the right to encroach on the state's individual laws--the federal agents should actually be arrested by the state police if they try to raid a dispensary.
So, where does this leave ecigs? Who knows!? States could ban them and the FDA could back them and we would lose, states could ban and the FDA could say they are okay, but states may still restrict them, the FDA could say they are bad but some states could still have them unrestricted. . .it's anyone's guess. I'd say the only thing that can be done at the moment is to fight at the state level while still massaging the federal level--it will probably take both to really give a final approval all around. Ain't politics grand?