It was never my grandparents in either side that kept us cousins close; it was our parents and their parents. I have over 40 first cousins. Some I have literally never met. A few are my very best friends, closer than my siblings. My grandparents' deaths were irrelevant. As kids, it was about proximity and our parents' closeness to each other. As adults, it's just who we like and shared memories from childhood that keep us together.
I take a short vacation at least once a year and visit several times a year with a handful o close cousins, others I see maybe once a year, some just at big family events or funerals, and some I've never met. We are Irish so the diaspora is wide: US, Australia, Dubai, Spain, Portugal, and of course Ireland and England. We still have a home place in Ireland.