Of course, one can only imagine whether or not they truly share an identity even now.
Some us might suppose that what it means to be human is in fact to create a diversity of histories, physiologies, and ecosystems. And that we will continue to do so whether on this planet or elsewhere.
You speak for a whole species? And the crux of your identity is the joy of wasting resources? What counts as waste or surplus depends upon knowing what one’s goals or values are, as much as it does accurate auditing of real-world resources.
Why do you suppose that someone else can or should decide this for you? It depends upon what kinds of descendants, societies, and ships you realize. The fact that we are %99.999 the exact same person, and yet differences in subjective values between us can yield entirely different trajectories of civilization is what I think makes the post-human diaspora so rich and compelling.