If Goldwater doesn't get the nomination then Reagan doesn't speak on his behalf and the GOP stays a more Moderate course for awhile.
Goldwater's nomination in 1964 reflected structural unease in the Republican party (much like Clinton's nomination in 1992); without massive changes to the underlying electorate, those tensions are going to be there with or without Reagan. My argument is those tensions would get much
worse if the conservative faction loses in '64, again, with or without Reagan. Ultimately they're going to get their man.
LBJ was going to win regardless of who was nominated, the public wasn't in the mood for 3 presidents within a year and the overwhelming sympathy from Kennedy's assassination. I don't agree that 1968 would be a lock for the Democrats, the Vietnam War and social tensions are still going to be around.
If Goldwater is the nominee in 1968, then LBJ could hold the Democratic National Convention in South Vietnam and still win 400+ electoral votes.
I'm just curious as to whether or not the Conservative wing would beat out the moderates, I could see the primary being Nixon v. Goldwater.
Well, I think you have two factors here: (1) all of the energy is going to be from the conservative wing of the party; and (2) if Rockefeller (or Scranton, or Romney, or some other moderate) is the GOP nominee in 1964 and gets crushed on the scale of OTL's Goldwater, then moderates will be perceived as "two-time losers" (Nixon and Rocky). Even more moderate supporters will be likely to give something else a try.
Again, I think this is analogous to the Democratic primary in 1992: lots of Democrats weren't exactly thrilled with the DLC, but after getting obliterated in '84 with an old-school liberal (Mondale) and beaten pretty bad in an otherwise-winnable year in '88 with Dukakis, even mainstream Democrats were (largely) willing to give the New Democrat Bill Clinton a try.
Also, without Reagan's publicity for supporting Goldwater in 1964, isn't there a good chance that his career in politics would be butterflied away?
Reagan was obviously
interested in politics pre-1964, and has (to put it mildly) pretty impressive retail political skills. I think it would take more than a butterfly to dislodge his career, although no "A Time For Choosing" speech might send it in a slightly different direction.