It is possible in the long term, but needs billions of dollars in funding, and a chain of strong candidates. I'd say it would take about 3 general elections or 12 years to change people's minds. A lot of America are die hard republicans or die hard democrats. For the first election, all a third party / independent will do is take away votes from the big two. But over time, with sustained campaigning and strong candidates, it should be possible to get a third party elected. But long term, this will have to be at the expense of one of the two older parties. We have seen around the world, politics filters down to two parties on the long run. The parties may change, but it's always two major ones in most countries.

As for this election, it's far too late. It's going to be Clinton or Trump.