Large families alone didn't make the Catholic Church endure. It was evangelization that made the Catholic Church great. Evangelization made it the universal Church universal - global in its scope. The Church grew because missionaries shared the faith, told its stories. We can't just rely on having large families to keep the Catholic Church great.
Large families are wonderful.
They're a blessing. But what will keep the Catholic Church great is a commitment to telling its stories, to evangelization, to witnessing. We all take things for granted. We take our families for granted. We take our country for granted.