The key is his worsening dementia.
As it gets worse they will begin to infantilize and forgive him.
Get ready for posts such as "We may have disagreed greatly, but no one deserves to have their mind taken away." getting gilded on reddit.
Trump will be placated and given the greatest treatment available and will somehow live into his 90s, despite his rotted mind, and will probably have some sort of playhouse where he can pretend he is doing a business like they did with his father.
I'm gonna go against the grain and say the libs won't rehabilitate Trump. Yes they rehabilitated Bush but that's because libs were all in favor of the invasion of Iraq at the time. Being able to redeem Bush is really just about them redeeming themselves. Or not, it's not like the libs are actually sorry about the invasion and the deaths of hundreds of thousands of brown people.
But Trump violates all their lib sensibilities. He's a physical manifestation of the people that libs love to look down on and feel superior too. I don't think they'll ever rehabilitate him since holding him in contempt will always serve a useful emotional purpose to them.