We have to speculate, of course. I always just imagined that, with Xena and Gabrielle dead to the best of everyone's knowledge and with Ares having vanished from Greece and Hera gone, Hercules eventually went back to Ireland to be with Morrigan since the big threats in Greece were gone and normal people could deal with the warlords.
Likewise, I thought maybe Iolaus eventually returned to Sumeria to be with Nebula.
Based on his last appearance, I guessed that Autolycus got remarried to his first wife and got into the banking business which he perceived as a legal means to be a lifelong thief.
I'd assume Salmoneus eventually got out of prison and continued his normal scheming to get rich to the very end.
Of course, there are all sorts of minor characters I wonder what eventually happened to them like Atalanta. Or what Eve eventually did.
I also wonder how Ares took it when Xena died in the last episode and if he was capable of communicating with her still.
Was wondering if other people made up their own explanations about things and what they might be.