Quite honestly, he'll be irrelevant to the bigger world so as the other Holy knights
Garling being promoted to Gorosei makes Holy knights worth dropped by huge factor.
Garling was the main guy that was given a spotlight and everything was build around him even before promoting to Gorosei, that's why him being the leader of HK is very much crucial (and enough) for not only him but HK as a group to be relevant.
Others members are seen as a background character at most.
They look insignificant compared to Garling.
Hence, many fans don't really give af about HK after the main plot guy leave HK much less who will be next leader etc (when we don't have any clue about the rest of em)
They'll be an opponent for Rev commanders like Morley etc. like if anyone interested.....