Kina er i færd med selvmordet.

The point is: The USA and allied powers do NOT want to repeat the mistakes of WW2.
Admiral Yamamoto had seen a window of ½ years before the new warships of the USNavy came into service.
The North Carolinas was actually commisioned BEFORE Pearl Harbor. The South Dakota's were coming on-line from March 1942. What was even worse from a japanese view-point was the Iowa's were laid down.

What was even worse - as it turned out - the Essex-class had not only been ordered in 1940 but the lead ship had by 1941 been laid down.

The japanese on their part: The Yamato class was just being commissioned.

China is realising, that the window of opportunity that Yamamoto used - it just is not there today. To make doubly shure the USA and the Quad is shoring up for any eventuality. China has lost the war before it even started.
The reason Japan initiated WW2 was that they could see the bottom of their oil tanks - plus the pitifull state of their lunchbox. China is in a similar situation today.

The further problem for China is: Russia has today not a fleet worth mentioning for the high seas. The Quad can even dispense with whatever force France could provide. Hence the childish tantrum regarding the nuclear submarines of Australia.

The chinese generals are not so stupid, that they can't see, that with India in a land war their army is without chance.

That was probably the reason why general Milley found it necessary to communicate with the chinese. The chinese feared, that the insane president Trump might attempt a preemptive strike against China to hang on to power. The chinese not being quite shure how the american system works - and feared that Trump would attempt a coup - which he did. I thoroughly understand the chinese apprehension.

The basic problem is the engines! An airliner only makes money, when it is in the air.
You can see the development in large aircraft engines:

The KC-135 airial tankers (entered service in 1957) originally with J-57 engines. It has been said that the KC-135 is a military version of the Boeing 707 - which it isn't: The two aircraft are structually very different - among other things the fuselage of the KC-135 is narrower.
In the 1980 the KC-135 was reengined with TF33 (or known in civilian use as the JT3-D), which is a much more fuel efficient engine - allowing a bigger off-load of fuel further away from base. That is: In reserve units!
But at the time the F-108 engines (civilian designation: CMF-56) were converted on to the fuselages of KC-135 fuselage.

As military aircraft do not remotely fly as many hours as civilian aircraft - it is simply the better performance of modern engines that makes the engine swap interesting.

The B-52 is now being retrofitted with the F130 (Rolls-Royce BR725) - which generally means the B-52 does not NEED as many tankers to perform their mission (thank God: The B-52 is a bitch to fly during refuelling).

The russian aviation industry struggles to keep up with the 1950'ies technology. Typically the russians have not been able to sell their civilian aircraft - even if they were basically donating them. You can't operate an airline profitably with russian engines - and with chinese production further stuff gets lost in the translation.

Those underslung engines of Boeing aircraft actually functions as counterweights so the wing does not have to be build as stiff - all the tests during the development of the B-52 was on the placement of the engines. So it is not surprising that the chinese run into engineering problems with that. It will get you in trouble, if you don't read beyound the summary of the instruction manual.

It is not a coincidence that the Indian Air Force bought the C-17 Globemaster III as a stategic airlifter. The C-17 is NOT a cheap aircraft to buy, but the capacity and performance makes it possible to operate more efficiently and bring loads in where the Il-76 cannot go. That is one (of apparently many) factor the chinese apparently have not calculated with in Ladakh.

India is following the Australian strategy - as long as the chinese maintain troops at the LAC they are just tormenting themselves with logistical problems - and getting themselves strangled by the inhospitable terrain. What India needs in the mountains to perfect this strategy is a lot of highly venomeous snakes - but that will not happen in Tibet - snakes frozen as stiff as a board are not very dangerous.