"No Justification Without Representation!"

I have a question for my Catholic Readers (with some preamble to set it up):

As I understand your position, the only hope for unity and genuine ecumenical progress is for us Protestants to return to Rome. The reason for this is that, according to you, the Reformation began with rebellion against lawful ecclesiastical power, and regardless of how long our subsequent history or how well-ordered our subsequent polity may be, there is no statute of limitations on apostasy. To put the matter simply, as long as the prodigal remains outside his father's house he is just that, a prodigal. Even if his pig-sty experience evolves into a great empire in which he becomes a mogul in the pork industry (even "the Sausage King of Chicago"), his success began with unlawful division, and this being the case, no amount of years can transform what is illegitimate into something legitimate.

My question, then, is this: What do you make of the United States of America? If the case can be made that the beginnings of this country were rooted in rebellion against lawful power (i.e., the Crown, an authority that, while not ecclesiastical but civil, is nonetheless divinely instituted), then it would seem to follow that, regardless of how many years transpire or how powerful we as a nation become, our only hope of gaining legitimacy would be by submitting ourselves once again to the United Kingdom against which we rebelled (over issues, I might add, much less important than those that compelled Luther and Calvin to break from Rome).

Since I honestly have no idea how tis question will be answered, I offer it merely in humble curiosity and not as some "knock-down, drag-out" zinger.

So what gives, Catholics? Are the rules different for civil power than they are for ecclesiastical, and if so, why? And if not, is not our Protestant nation even less legitimate than our Protestant churches?