Downgrade iCloud storage after purchasing apple one?

Years ago my husband bought a 2T icloud storage plan which we pay $14.99 monthly, (It's actually ridiculous because he only uses <60Gb).Later when I got my 1st iPhone, I got an Apple Music family plan to share with him and am "the family organizer". I recently upgraded to Apple One family. My question is, if he gets rid of his icloud plan, will his files & photos still be right in the cloud under my plan? I would be in trouble with him if he lost his work photos. His apple id is the same as it always was. Is there anything special I have to do to ensure his files aren't lost in the switch?