LBJ Dies Sometime Between December 1965 And December 1967.

[Glass Onion]

I've already asked about the consequences of a Johnson death in 1968, and I was wondering what the effect, if any, would be of an LBJ who lives long enough to have the high points of his Presidency, but not long enough to live to see 1968. I know, embedded here are various different scenario's with very different consequences. But it made more sense to give a range rather than to create multiple threads. So, my question is as the thread title suggests. Anytime between December 1965 and December 1967, President Johnson has a fatal heart attack. Vice President Hubert Humphrey is sworn in as his successor. I know random heart attacks are not the best tool in our kit, but considering Johnson's health history, in his case I think there might be some justification for it, especially given he had already suffered one in the fifties. While the answer to these questions will differ based on the precise date, I do have some very general preliminary questions.

1. How is Johnson viewed in the years following his death?
2. What of now President Humphrey? How does President Humphrey deal with the Vietnam mess he's inherited? And how long would his honeymoon period as President last? Would President Humphrey be able to keep the nomination? Would he be able to keep the Presidency?
3. How would Johnson's death change the 1968 political calculus if at all?