Let's say Patterson successfully defended against Liston. Would Ali have fought HIM for the Heavyweight title?
More likely than not yes. Unless someone stepped in sometime between 1962 and 1964, and managed to pull off an upset.
If Floyd Patterson defeated Sonny Liston in September 1962. We would have definitely seen a Floyd vs. INGO IV bout in early-Summer 1963. INGO was still the 'big money man'. Probably a bout in Stockholm, Sweden with about 80,000 turning out for the event.
What if Patterson had the chin of Vitali, the power of Wlad, the stamina of Salvador Sanchez, the defence of Whitaker, the offence of Hagler, the skills of Duran? He didn't so he got beaten, the end. Ali would have fought him btw, I'm sure about it.