Today the Vatican is a sovereign country the size of a neighborhood in Rome. But from the Middle Ages up until around 1861, the Pope directly ruled a large chunk of Italy known as the Papal States.
And don't forget that medieval Popes could do things like make a speech that launched the Crusades or write a papal bull that established the Spanish Inquisition. Even in those brutal times, only really powerful people could tell whole kingdoms to invent and use super creative torture methods.
Modern popes lead a Church that isn't shrinking as fast as people say, but isn't growing all that much either. Church-affiliated university research suggests that Catholics have held steady at around 17% of the world's population over the last few decades. Even the American part of the Church has reasonably strong numbers, but its members attend Mass less and less frequently and want more modernity in their faith. Heck, even the nuns in American Catholicism are too liberal for the pope's taste.
Still, despite the Church's sex abuse scandals and factious politics, the Pope is the recognized spiritual leader of well over a billion people. And you don't draw a crowd of 100,000 for your farewell message or fill Yankee Stadium for a Mass if you're the head of an irrelevant, long-dead institution.
Anyway, that's a taste of what the new pope will have in store for him. Best of luck to whoever it turns out to be, because being the most visible member of any church is never easy.