You wouldn't get a one-party state. The US did this before: back in the 1800s, there were 2 parties, the Whigs and the Democratic-Republicans. The Whigs imploded, so the other party broke in 2, yielding the two present-day parties.
If the GOP were to collapse and die out (as it should), the Democratic Party would simply break in 2, creating two new parties: the left-wing/progressive party and the center-right party. The former would champion all kinds of social causes and the latter would be the pro-business party.
If the GOP were to collapse and die out (as it should), the Democratic Party would simply break in 2, creating two new parties: the left-wing/progressive party and the center-right party. The former would champion all kinds of social causes and the latter would be the pro-business party.