My point is that by 1776, the genie is out of the bottle, no? You have decades of joint-colonial action, plus people from the colonies traveling to universities in other colonies, as opposed to back across the water...
By 1776 you have anout a decade of joint colonial action, and only half of that was consistent. Several colonies were not represented in the Stamp Act Congress, I believe.
And what you're arguing isn't that they just have some semblance of American identity, but that identity is so strong that they will insist on political unification to the extent they are willing to risk another destructuve war over it even if their other concerns are met. I just don't see it. If they are moving towards responsible government, colonial level identity is encouraged, and divisions between the states are flagged, I just don't see the push being that strong.