Only God knows the future and what our country will be like a century from now. We can speculate and make guesses about the future but that's all they'll be -- mere guesses.
But God not only knows the future, He also is in control of the future! I know that may be hard for you to accept because you know how much evil there is in the world and how much chaos evil men can cause. But behind the scenes, God is sovereign, and ultimately the future is in His hands -- and that should give you hope. The Bible says, "He sits enthroned above the circle of the earth.... He brings princes to naught and reduces the rulers of this world to nothing" (Isaiah 40:22,23).
Does that mean we should sit back and be unconcerned about the evils around us? No, of course not. If anything, those evils should make us pray harder and work harder for righteousness. Any nation that turns its back on God and His moral law eventually ends up in chaos -- which is exactly what Satan would wish for us. The Bible says, "Righteousness exalts a nation, but sin is a disgrace to any people" (Proverbs 14:34).
Don't worry about what the world may be like 100 years from now. Instead, be concerned about the present, and ask God to help you declare Christ's light and life to those around you who need Him.