Ron Fournier has this essay in National Journal. Near the bottom, he suggests reasons why a new major political party in the U.S. is not entirely implausible. Fournier is the former Associated Press Washington, D.C., Bureau Chief, and now writes for National Journal.
The article’s title is misleading. Even if one major party died off and were replaced by another, that would not alter the existence of the two-party system. “Two-party system”, a term invented in 1911 to describe the British political system, simply means a system in which two particular parties are substantially larger than the other parties. Thanks to Peter Gemma for the link.