It would almost certainly result in a massive spoiler effect, handing the Democrats a landslide victory, unless the Republicans managed to completely and utterl

It would almost certainly result in a massive spoiler effect, handing the Democrats a landslide victory, unless the Republicans managed to completely and utterly drop the ball in putting forward a candidate that could beat Trump in at least a few states. That latter scenario would mark the death knell of the Republican party as an institution, leaving a power vacuum that Trump-aligned fascists would fill with an even further right party. First-past-the-post voting makes the 2 party system inevitable.