I do think sometimes the end of a character's playability is reached. Sometimes it is just in one game, and sometimes it is complete. I have retired more characters that I play, truly, or put them aside because of circumstance, and I never find it easy, or welcome, really.

If you feel it is time to retire him in Milliways, then maybe it is. I hope you can find another venue to play him, or another character to play, that will fill you with as much joy as he has.