I think that the Democratic Party devolved into being ndearly identical to Repubicans when it ended it’s relationship with unions in the 90s. We are feeling the consequences of the Bill Clinton years during which Clinton assimilated Republican ideas like NAFTA and welfare reform for the sake of staying in office and thus retaining power. Clinton’s argument to Democrats is you have to be in power to affect change, but the consequence was a near equivalency to Republicans. Now Democrats are unable to fight for anything because their real constituency is the same capitalists as the Republicans.
In the past, replacement parties would evolve as a fix to when a party goes off the rails, but with the current election laws and the amount of money they involve, the power class has a strangelhold on the United States. The Supreme Court, particularly as it is constructed, is all about returning the country to when capitalists had no restrictions.