The main requirement for more diversity in the US system is ranked choice voting. Without it, people are forced to vote pragmatically for the lesser of two evil

The main requirement for more diversity in the US system is ranked choice voting. Without it, people are forced to vote pragmatically for the lesser of two evils rather than according to their values, and no party other than the two entrenched ones can get any traction. Needless to say, this is unlikely to change without a fight, since the status quo benefits the people in power on both sides.