In regards to Trump, I think what this election showed is that unlike in 2016 when the opposition to Trump was divided, nearly all of those who oppose Trump are, for now, supporting the Democratic Party. Even if Trump were to completely hold his base, based on the midterm result, he would still lose reelection.
This is why the Atlas/pundit #hottake about how a third party candidate hurts Trump is so tiresome. Trump's 45% base is locked the f**k in. Any division of the remaining 55% only hurts the Democrats.
That's an overestimation. It's more like 35-40 percent. His 100% hardcore base is a couple points below his approval ratings, which tend to be between 39 and 42.