Social Cohersion in Orbit

Let's look at the USA as a model, which seems OK to me as most SSI members
are from the US (I assume) and so might have little familiarity with the
history of other countries (assumption 2), and most of the colonists will be
from the USA and will bring their historical (mis)understandings with them
(assumption 3). Sorry if this is offensive - I find it hard to judge SSI
members from the few posts I see on this list.

IMHO, the US war against imperial rule was so successful because the 13
colonies were able to band together against a common enemy, who was
geographically distant, and had plenty of rivals in Europe to keep them
occupied. I don't think that this will occur for the orbital habitats, as
there won't be a common enemy, although they will be far away, and will have
enemies to keep them busy. For colonies to join into a Union, there has to
be some value in them doing so, and having a common foe or opportunity will
help. More likely, if the Earth were to fall into political chaos, there
would be a stronger cause for the habitats to band together.

The Federation of Australia was formed by the colonies agreeing, albeit
temporarily, that uniting to form a single economy and military was a better
strategy in an environment where the mother country might be less able to
help us in a time of crisis.