Ironically, the amount of damage done makes it almost fixable. Trump going so far off the deep end will eventually allow whatever conservative political body forms after he’s out of public life to disavow Trumpism.
Compare the Trump movement to the Tea Party movement and you’ll see what I mean. The Tea Party wasn’t too far away from the existing Republican platform, and the movement was comparatively tame. Because of that, the Republican party would not be able to separate itself from the Tea Party movement if they tried.