The suggestion there's some sort of wave of Democrats splitting for Trump is laughable when there's no ideological alignment between even the most centrist Democrats and Trump. The few jumping over, like Gabbard, are the most cynically hollow of politicians who have no political ideology to speak of, simply chasing what's best for their profile.
With the Trump campaign floundering and a Harris win looking more and more likely, I think even the most vapid and opportunistic of them will be thinking twice before jumping ship now.