I don't see this possible with Khomeini seizing power or his disciples staying in power. Khomeini consolidated power very quickly upon his return to Iran in January 1979. He eliminated the provisional government under Bakhtiar by February, and got his Islamic Republic referendum passed in March. Khomeini's initial choice for PM Mehdi Bazargan was a democratic figure, and he lasted only until November when the Hostage Crisis happened. Khomeini needed an outside enemy to rally people to his banner, and the US was the best choice as a close ally of the Shah.
Once Iran is established/consolidated, I don't see the clerics letting go. There were possible overtures to Iran after the Persian Gulf War and 9/11 Attacks that might have resulted in some kind of US-Iranian detente, it is by no means certain the most likely result would be a US-Iranian alliance. The best chance is to kill the Islamic Republic before or at its birth which means Khomeini has to die before 1979.
The revolution against the Shah was not initially in favor of an Islamic Republic. Many secular moderates and democrats (and the Western media) viewed Khomeini as a moral figure, but not a politician interested in power. Their intention was to establish a democratic Iran. However, Khomeini was too smart for them, and he cleverly exploited discontent to become the dominant faction in Iran who then eliminated everyone else. If Khomeini died in 1978 somehow (either naturally or by assassination), it wasn't going to stop the Iranian Revolution, but it probably would stop it from becoming an Islamic Revolution.
A lesser possibility is that Bakhtiar takes power in a way that does make it seem like he was the Shah's prime minister, but done in opposition to the Shah, and this allows him to consolidate power in a way that defeats Khomeini. However, I think Khomeini is just too skilled to allow himself to be outmaneuvered by that, which is why I think he needs to die before he reaches Iran.
If the moderate democrats remained in power and guided Iran to stable politics (which is what the Carter administration assumed would happen), then an Iranian-American rapprochement is probably inevitable and would happen by mid-late eighties. A return to some kind of alliance would eventually happen. If the Iraqis invade a Bakhtiar lead Iran in 1980, then the US might even assist Iran in various ways early on, and the reconciliation might happen sooner.