Yea - I think I remember experiencing that myself and have heard others speak of it. I think it's more just that "brave new world" phenom. Like you said - the only experience most of us have in 'letting go' has ended up in a shrinking or dissolution of things.
This is really different.
It's more about letting go of mutual 'anchor points' if that makes sense. We're untying from the dock, going sailing in different ships. The plan is to stay together and eventually reach a new port. A natural worry that a storm may blow in and send us in different directions is likely to be there. But we have to believe that if that happens, we'll get back on course and still end up at the planned port - just maybe at a slightly different time. Trust.