Krepinevich's analysis of Russia is similar to Nextbigfuture. Nextbigfuture had noted that long term low oil and gas prices and shrinking population are trends that will weaken Russia over the coming decades.
Nextbigfuture also notes that the USA and China do not need to fight or have conflict. The USA and China can both be economic winners who prosper in peacetime.
The USA and China are nearing economic and technological parity. China's military strength will lag the USA for about 20 years.
China is still behind the USA in several technological areas. In particular with large airplane engines and with aircraft carriers.
However, the gap is closing and China is competitive with the United States on overall scientific research budgets.
Europe was able to mount a program to create Airbus and become competitive with Boeing and has continued to match Boeing airplane technology.
There is no reason to think that the US will be able to create a sustainable military dominance like the 1990 to 2015 period while China is an economic and scientific research peer.
Any leads will be temporary and copied by the other.
China is still projected to average 4-6.5% GDP growth for the next decade while the USA is projected to be at 1-3% growth.
China has surpassed the USA on purchasing power GDP and will likely surpass the USA on nominal GDP in the 2025-2030 timeframe.
Krepinevich is at odds with defense officials like Chairman of the Joint Chiefs Joseph Dunford, Army Chief of Staff Mark Milley, and Defense Secretary-designate James Mattis, who all put Russia first. Mattis is also a hardliner on Iran.