I've been astonished at his rate of deterioration. I thought when I he first won that he'd be a vegetable by about year two of his presidency.
I compared his speech patterns between when he was a presidential candidate and several years ago when he spoke at length to Howard Stern. He was an infantile jerk then, too, but he could string long paragraphs together and maintain the thread of conversation.
Fast forward to the campaign, and that capability was completely gone. So it stood to reason to me, since I've seen dementia up close in person (no, not me! yet) that he'd not last through his presidency.
I think it's starting to hit, though.
You're probably right about the crimes. Even if charges are brought, by the time that happens he won't really understand what's happening.