That era had lots of talent in the heavyweight division, but Ali and Frazier stood out from the rest of the pack. Foreman came at the tail end of that era (early 70's) and he was a total beast too. Foreman was never given as much credit for his boxing skill as he was so powerful that after 3 or 4 rounds his opponents usually looked like stuffed animals that had been run over repeatedly by a tractor trailer.
In the mid to late 60's, in addition to Ali and Frazier, there was Oscar Bonavena (from Argentia I think) and George Chuvalo (Canadian). Bonavena was a pretty good fighter. Chuvalo was a punching bag but he always put up a good fight. Jimmy Ellis was a very good boxer. Frazier beat Ellis for Ali's vacant title when Ali was suspended. Buster Mathis wasn't a bad fighter either, and Jerry Quarry was an excellent all around fighter. He's been called the greatest heavyweight that never won the title.
If Frazier is in Hospice, it is the end. Pain control is the only concern. My dad was in hospice at age 92. Unfortunately Frazier's athletic heart and lungs will prolong the end. My dad's superior fitness resulted in him lasting 8 days in an unconscious state with no food, water or IV. Brutal stuff. Let go Champ. Time to throw in the towel.