For me, all they have to do is admit they were wrong and be willing to hear how "liberalism" would be good for them.
That last part, I believe, is crucial for America's detrumpification. No longer can Democratic Party elite or the "left" just flyover the "red" states and allow them to fester in poverty, ignorance, and mental illness. To use Christian terminology, we need missionaries to proselytize and evangelize the south and the midwest.