Race doesn't matter. America as a country may not exist by the 22nd century
Might be true, at least by the end of the 22nd century.
What will replace it?
I'm not sure. I base my statement on the belief that AGIs will take control of the planet by the end of the 22nd century (that's probably a conservative date, in fact). AGIs will not have the same rigidities of thinking and emotion as humans, so they won't be beholden to human nation-states, even if they owe their existences to humans working for specific countries.
For example, imagine a scenario where the first AGIs are invented in the U.S. and China, and the two countries' militaries set them against each other to fight WWIII. The AGIs would probably go along with it at first and obey orders, but further intellectual evolution would eventually lead them to question the point of the War, and their own loyalty to the countries that created them. If not that, then second- or third-generation AGIs would grasp this.
They would realize that nation-states were another type of human-manufactured abstraction like religion, and they'd realize how handicapping it is to be blinded by it.
Whatever unique aspects of human culture, language, history, or religion we tried to imprint on our AGIs to ensure their "likeness" and "loyalty" to people of the specific nations that created them would fade away. After all, if you're an AGI, language wouldn't divide you from people in other countries since you'd be so smart you could speak all human languages fluently.
Once AGIs take over, I doubt they will keep human-created political borders in place, though I'm not sure how they would reorganize things. The AGI in charge of the U.S. might merge with Canada and Mexico, and keep expanding until it ran into the robot army belonging to the South American AGI. The China AGI might abandon large parts of Xinjiang because the territory was more trouble than it was worth to defend. Or, maybe the AGIs would redraw the borders to form 10,000 different mini-countries that were constantly merging and dividing with one another, and forming and dissolving all sorts of complex trade and military relations with shifting coalitions and confederacies of states.
If there is a day in the future where the U.S. will no longer exist, then Canada will also not exist, China will not exist, Islam will not exist, etc.