As I'm sure you know, there is no rule that says we have to have a two party system so how are you going to "dismiss" them when we are all the ones keeping them there? A single vote for republicans or democrats doesn't have any more power than a vote for a third party. You don't get extra points for voting for the winning team. The two party system will end as soon as the American public decides to end it.
So if every American voted for a third party candidate in every election possible, we would still be left with a two party system? Can you explain further because I don't understand how you are reaching your conclusion that it is impossible to change from a two party system.