According to a thread on the totalwar.com forums citing a PM from a CA person, the United States will only be playable in the mini-grand campaign that comprises the 4th chapter of the Road to Independence, running from 1783-1810. It will not be playable in the main grand campaign from 1700-1799.

I wanted to comment about the faction preview:
After the French and Indian Wars, the British government took an entirely unreasonable line: the American colonists should pay taxes to contribute to the navy and army that helped defend them. After all, those colonial fellows enjoyed the benefits of peace, protected by Britain’s expensive soldiers and sailors. The colonists had other views. The British responded with political stupidity and military ineptitude.
The sarcastic part about "an entirely unreasonable line" is such a typically myopic view often seen in British historical texts' commentary on the Revolution. The objection, as any American 8th grader should know, was not to paying taxes at all but having no representation in the Parliament that levied those taxes. The slogan was "no taxation without representation," not "no taxation."

Most American colonists didn't even necessarily want independence at first (except for a few hotheads), just equal rights and representation as the Englishmen they perceived themselves to be. When it became clear the Crown and the majority in Parliament would refuse to grant that representation, second-class citizenship seemed permanent, and any effort to return to some semblence of the self-governance the colonies enjoyed pre-1763 seemed futile without independence, thus moving even conservatives and moderates like John Adams to support independence reluctantly.

Moreover, while I grant the indispensible role of the Royal Army and Navy in protecting colonists from the French and Indians, the view in the faction preview and many British history texts overlooks the key role of colonial militia in the French & Indian War, militia paid for and manned by colonists.

That said, I wholeheartedly agree with the faction preview when it says, "The British responded with political stupidity and military ineptitude," both of which were vital to American victory!