> He's convinced them that he is on their side reality be damned. It is too painful and hopeless to countenance the other.

That sounds less like tribalism than like desperation to me. And in any case, what difference does it make? Either way, it boils down to a stark choice: on the one hand, the Democratic Party may work out how to offer a credible alternative to Trump - more accurately, to whoever comes after Trump, and will no doubt be to Trump as Trump to Bush - and on the other hand, the Democratic Party may watch impotently as events continue more or less as they have done.