Russia, Iran, and several ex-Soviet republics have huge reserves of oil and gas and are commercial partners of China. I don't see any of these bowing to US pressure to stop selling to China. And all can deliver via land routes.
India is great-ish in rockets/missiles, but in aircraft (and tanks) not so much.
And is crap in aircraft engines. Ok, this last one is one of the most difficult if not the most difficult thing to master.
LOL, and how many tens of thousands of fighters with liquid-cooled engines are produced during WW2?
Almost all of the British Bombers, half of the German ones, and almost all Soviet bombers also used liquid-cooled engines.
Relegated, indeed...
Maybe. I remember the assumptions about the Soviet Union that proved wrong - to be fair in both directions - after the fall and consulting the soviet records.
Sorry, you have work to do at home.
Write an essay of at least 50 pages, reporting how many times people with your job has been wrong, and why in the last 50 years.