I caution all my friends that it is only July and we have a long way to go before the election. A lot can happen.
Never underestimate Democrats ability to create a false narrative and their media pals to push that narrative until it becomes fact. They have done it time and again. I believe if Biden decides to stay in this race, and I think he will because Lady MacBiden will not give up her power, Democrats will eventually circle the wagons, consolidate their messaging, enlist a compliant media, and turn the debate fiasco in to a "one bad night". And we all know they can pull it off because their supporters are gullible. The narrative will go back to Biden is sharp, he had a cold or some other lame excuse, and they will go back to hiding the truth from the public. Biden will go back to campaigning from his basement, only coming out between 10 am and 4 pm, on days when he is functional. No one will question this or call him out. Instead, the focus will be on Trump is a would be dictator who will end Democracy, a rapist and a convicted felon.
By November, most voters won't even remember Biden's debate performance.