It may just stay in the bed and that's the only place that the child will use it. But certainly, as children develop, they develop alternate mechanisms for dealing with a distressed situation. Very, very definitely. It's not only this one object or the one object and mom any more. As children get into school, they make friends.
Friends can be a useful source of comfort and soothing.
Certainly cognitively, once children get to be about five, six, or seven, they're able to think of alternative explanations for what's going on. So a situation that might have seemed very threatening as a preschooler, would no longer be quite as threatening. And by that you mean a typical thing - two children squabbling and fighting over a toy or something. The child will interpret it in a different way so it may not be quite as threatening. But the child also has alternative strategies for dealing with unpleasant situations, things where he might need some comforting and soothing.