When you buy something do you hope it will last forever? I do. The new lawn mower. The expensive car. Even the shoes I love.
Not much stays as beautiful as it was when it was new. It wears out and breaks down. But a picture book, that's something different. If you can manage to write a classic it will be fresh and new to every generation that reads it. People will come back to it to read it to their kids and grandkids, give it as gifts, share it with friends.
Just write a classic. Is that too much to ask? Sure, but as writers it's something we strive for. No harm in aiming high.