LBJ dies exactly ten years early

[True Federalist (진정한 연방 주의자)]

First off, let me address the obvious elephant in the room. While butterflies are likely to change the date, Kennedy will still be making an appearance in an open convertible in Dallas in Autumn 1963. The electoral map dictates that Kennedy lock down Texas if he can, so campaigning with potential running mate, Governor John Connally, will happen.

Whether a Kennedy assassination attempt still happens or it has the same results can't be known.

If it does, then Speaker John McCormack becomes the first President since Grover Cleveland to be from the same State as the previous President (Chester A. Arthur), and Carl Albert becomes Speaker seven years early.

McCormack probably has no choice but to run for President in 1964 despite his age, but if he still faces Goldwater, he should easily win.

However, with neither JFK nor LBJ running, it's less likely the Republicans nominate Goldwater to be a sacrificial victim in the inevitable loss, since McCormack won't be an inevitable victor. Against President McCormack, I think Nixon tries again, but might not get the nomination.

If Kennedy survives or isn't shot, then 1964 is likely a Kennedy-Nixon rematch.

I've laid out the starting points, but don't feel like picking paths beyond them.

[True Federalist (진정한 연방 주의자)]

Speaker McCormack becomes acting prez in Nov 1963 and RFK is elected 36th prez in 1964 in a landslide.

No. RFK had no chance of becoming President in 1964. Schlesinger likely gives him the same advice as in OTL, so he becomes Senator from New York, the same as OTL rather than being anyone's running mate. While butterflies could lead to him becoming President in 1968, 1964 is way too soon.

[True Federalist (진정한 연방 주의자)]

Does that scandal get butterflied away?

Which scandal?

[True Federalist (진정한 연방 주의자)]

The Gulf of Tonkin incident likely doesn’t happen under President John McCormack, which butterflies away full-scale US involvement in the Vietnam War other than having a contingent of military “advisors.”

What makes you think McCormack gets rid of McNamara? While it is plausible that McCormack reacts differently to the Gulf of Tonkin incident, it McNamara is still Secretary of Defense, the incident still happens.

[True Federalist (진정한 연방 주의자)]

All this is to say I think it's highly likely that the assassination is butterflied away. And even if it's not, maybe JFK appoints someone else as VP first, so whoever that is becomes President instead of McCormack. True, LBJ didn't bother to appoint a VP until he and Humphrey won the election, but maybe JFK would if it happened nearly 2 years before the next election instead of less than 1.

There was literally no way to appoint a Vice President before the 25th Amendment... it's not that LBJ "didn't bother".

My mistake. It’s possible this speeds up the adoption of a similar amendment, howver.

Doubtful. The major reason for the passage of the 25th was not to provide the means to appoint Vice Presidents when that office was vacant, but to provide procedures for how to deal with an incapacitated but still living President. A very real possibility had been that JFK could have been severely brain-damaged by the bullet but not killed.