That is going to help Democrat party seal the future for them as well. We are going to see the whole nation who are against this new Republican party at the Democrat party, not like they were so awesome before, but right now the in fighting of that party made it even worse.
There is also the one where he fell from the bike as well. He is old, he is definitely very old, there is no doubt about that. However, at this point Republicans are a bit more in trouble than democrats about it, why? Because imagine a country that voted for a guy that was too old to do the job, instead of picking their candidate who was on a reelection campaign.
Trump had 4 years of presidency, and yet he couldn't get reelected against a guy who can't even finish a sentence. This is why it's quite important to realize that Republicans are responsible for finding a candidate that could actually get the votes to win, otherwise they are going to lose again.
Just from a strategic point of view I think you hit the nail on the head. Trump is polarizing the people and polarizing often means that half of the crowd loves you and the other half hates you. That is essentially the goal of being a polarizing character. The advantage is that you have hardcore advocates guaranteed. When you are a handsome guy you might not be heard enough and just drown in the noise that others make.
In this case it is true what you say, the Republicans shouldn't want a candidate who polarizes. They would be better off with a candidate who is more handsome like Biden, but more energetic and enthusiastic. That could take votes away from the Democrats.
Something I am not sure about yet is if Biden is going to try it again. I think it is a tough call and this is not because I think he is a bad president, but age will come into play especially for him (and already is), and we are not talking about another year of presidency, but five years. I would even say it would be undeserving if he had to cancel his presidency in the middle of his term.
Hard to say, but despite his age I think he is doing a good job. He is shaky in his voice, and shaky with his body, sometimes shaky in his mind, but his political content and strategy isn't.