Wrong.
With economic might comes technological might. Both those things combined gives you military might.
As China rises economically, China will catch up technologically in all areas. Once you have the money, you can develop technologically as you have more money and more companies develop the technologies. Military power is about how advanced you are technologically and how many of each weapon you can afford (numerically).
China will surpass the US economically, financially, technologically and militarily. These combined will give China enormous political power globally just with the hard power alone.
Allies comes from hard power (size of consumer market, investor, financier, technological provider, aid provider, weapons provider). Countries will move towards the country with more comprehensive hard power. Values are not as important when you are outmatched in hard power. Values and culture are like extras added to US hard power. Without hard power, you cannot be influential. Switzerland has far greater values than the US but have no hard power as a foundation.
US will only have the advantage over China in cultural power (movies, tv, music, etc) due to English being the global language as its very easy to learn.
And yes, the US is very much in decline and the process is getting worse for the US. US middle class is shrinking, the debts are mounting, growth stagnating even with loose monetary and fiscal policy, wealth is moving to the top 1% even as a fully developed country, socially being destroyed with crime, drugs, the destruction of the family unit, becoming welfare state, higher population of blacks and hispanics, etc.