If Ali accepts induction - what happens to his career and the HW division?

If he accepted induction, he would have served 2 years, not had any title defenses during that time, but would have given a bunch of 3-4-round military exhibitions, his title would not have been stripped, and he would have resumed defending once discharged from the armed forces. He still would have lost a little something, but not nearly as much, because he would have been more active, and had less time on the shelf. So ultimately he winds up with a lot more successful title defenses than he had.