Not even close to viable. At least, not if polls in the US are made by anywhere the same rules as we use over here.
Internet polls are by and large fairly useless. Not only is it easy to cheat, but when you have no control over who you ask and who they are, it might as well be random numbers.
Not only highly doubtful, but not at all.
It gives us a good idea about how the "regular" posters of ENworld feel. Because lets face it, those who post are those who vote. Question is, are we a good representation of those who play D&D (whatever version) - I doubt it.