The support Trump gained is definitely not "Republican" support. People are starting to see through the uniparty facade.
Trump broke the republican party.
Bernie could've broke the democrat party in 2016 but he took the money and ran.
The foundation is getting shaky...
Folks hoping for a multiparty system won't get it within our current structure. Our current system of government makes it where either a single party or two-party system will be the norm. The reason being is that it's not proportional but first past the post. The only way we can get a multiparty system is with a ranked-choice voting system and probably something more representing parliament as they have in many European countries and Canada.
We would be much better with a parliamentary system. Our society has gone through multiple political parties between the whigs, federalists, and the Democratic-Republicans before they split but it always ended with only two-party reign for the most part. We need to get rid of this system that is winner takes all and make it more representative.
If the Republican party or the Democratic party dies, then something else will just fill the void just like the three examples I mentioned.
Our system is fundamentally flawed from its inception and even the "founders" warned of the dangers of a heavily partisan two-party rule in the future. A formidable third party is impossible unless you get rid of the power concentration that occurs in this type of system.