Yes, it's the inverse of that other thread.
In wuxia fiction, there are some main protagonists who go on to appear as supporting characters of other stories. In the Jin Yong universe, Gwok Jing became a major supporting character in ROCH after having headlined LOCH, and Chan Ga Lok stepped down from the main character role in BOOK & SWORD: GRATITUDE & REVENGE to a supporting character role in FLYING FOX OF SNOWY MOUNTAIN. Over in Gu Long's universe, I believe Lee Chum Foon showed up in a story or two that didn't feature him as the main character, and Tse Hiu Fung went on from being the main character of THIRD YOUNG MASTER'S SWORD to a supporting character in FULL MOON, CURVED SABRE.
What other main characters who did not appear as supporting characters in other stories, however, could have been good supporting characters? To be a good supporting character, the character must not steal the thunder from the real main character, but must somehow facilitate the story of the actual main character.