The election of Trump was the solidification of that era, not its beginning. The American democratic dual-polity experiment failed on November 4, 2010. That day, Mitch McConnell stated openly and without remorse to a group of journalists that "the single most important thing we [Congressional Republicans] want to achieve is for President Obama to be a one term president". This statement showed plain and naked for all to see that the era of a nominally functional two-party system in the US consisting of a ruling party and a loyal opposition had died. The divisions have only become more stark since. Trump is not the problem, Trump is one of the results of the problem. The division of a state between two competing views is not inherently impossible to make work, but when even one side states that they have forgone all attempts at compromise and seek only the removal of the other from power, the balance a two party systems collapses into tribal warfare. The next election the US has is not a watershed moment marking a potential loss of democracy, that moment can be traced to the corporate funded Tea Party and Citizens United issues of the early 2010s, in which the wealthy pried their way into a stranglehold on the economic functions of American political structures to the point of completely infecting the system at its core. This issue can't be resolved through voting any longer, as the tribal outlook has infected the voter base as well, and will take a miracle of cooperation and patience to right the ship and provide democratic voice to the citizens of the US again.