Children aren't the future of the Church - they are already the Church. They are not a group to be set apart, a group for future reference - they are part of the Church now!
What has the past 40 years of separating our children from us at Mass done to our children? Let me rephrase...what good has come of it? We now have grandparents, parents, and children who are apathetic and listless about their faith. We keep demanding less and less of our children at Mass.
For instance, I saw a lady take her four and six year old to the nursery this past Sunday. Never mind the sign that says "For children and infants 3 years old and younger". Yikes lady. If your six year old won't behave at church, maybe you should come to church more often, and not let him go have playtime at the nursery.
Thankfully, our parish doesn't have children's liturgy of the word any more (not because they think it's wrong, though, but because there is no one interested in running it). What a nightmare children's liturgy of the word is. What does it teach our kids? Arts & Crafts? Dumbed down, watered down faith? Well, I don't want that for my kids. So they will stay with me during Mass.