A thought I've vaguely sketched out in my head, but not gone much further than that...
Assume that Alexander's illness of 323 is debilitating, but he manages to recover. He's around for the birth of Rhoxane's son Alexander IV, and sires another child or two, either on Rhoxane, or his Persian wives, or a combination. The Arabian expedition takes place in 321 and 320, and sees the Arabian coastline notionally bowing to Alexander's control. The last couple of years of Alexander's life are spent putting down minor revolts across the Macedonian Empire, and he dies sometime around 318 from a wound sustained in a skirmish.
How do those who know more than I about the early Diadokhoi imagine things are going to play out in this (admittedly vague) scenario?