I tend to think that the "Trump will seize the presidency" is akin to the "Trump is a fascist" narrative which is only a hop and skip away from the "Trump is a Russian stooge" narrative.

Notice how little we hear from Democratic messaging about Russian interference or impeachment? Clearly this must not have tested well when they were vetting their messaging against test audiences.

My guess: the idea of some refused succession is all bluster and fantastic delusions of media-elite liberals, unable to imagine a reality that's not all-out emergency.