Unless Goldwater straight up ridicules JFK during his death (which given Goldwater's personality is unlikely), Goldwater would be likely to still emerge as the front runner. Rockefeller was too liberal for a large section of the party to pallet by 1964, Smith was a woman who faced only an uphill battle against the chauvinistic Party Establishment, and Nixon would still want to keep a low profile to lick his wounds and recuperate. Lodge would be an interesting choice, and would likely be able to pull a larger popular vote than Goldwater, but Johnson would pull through.
Kennedy would be remembered as a tragic progressive who was cut down before his time by illness, although won't be considered as notable in ITTL given how undramatic his death is. The mixed response many had towards him would not evaporate. Johnson picks up where Kennedy left off and pushes the CRA through with brute force (though with more difficulty than IoTL).