Awesome
, before continuing the debate I should mention I do think your timeline is great and am not criticising, just being devils advocate (and yes I am from the CW so I do have a vested interest). My automatic response to both is, are there examples in military history of countries fighting long wars, developing tactics and doctrines then ignoring and or forgetting them / learning the wrong lessons, especially in the 20th & 21st centuries (Britain & France after WWI, US in Vietnam vs US Iraq MK II). China, again, a war happening on the other side of the world taking the right lessons from it rather than ignoring or learning the wrong lessons, examples from history, 19th and 20th centuries never mind further back (US Civil War demonstrating Trench Warfare, French and British experiences in Vietnam and Malaya respectively prior to US involvement in the former).
I do take one other point without contension mind, even with a meteor engine, don't get me started on the Crusader lol.
Incidentally, as you mentioned, I am not arguing the US will not win, just how much it will cost them to win. On equipment, given the veteran status of the CW troops, surely they would know how to destroy the majority of their equipment as they retreat, unless you plan to make this a North American equivalent of the 1940 invasion of France? Even then, they hardly have Dunkirk to retreat to so may as well destroy their equipment rather than abandon it to get away by sea (granted destroying rifles is not practical but, vehicles and ammunition sure) Especially the radar system, would there not be directives to make sure that does not fall into enemy hands at all costs?
On the airforce, I was not arguing lack of capability, although again there are examples of learning air combat tactics only to change them and having to learn the hard way that the old ones were better (think RAF V formations for fighters rather than wingman pairs and 4s in the Battle of Britain). I was thinking more political necessity, the same thing driving the bombing of London in 1940. The RAF is nearly finished operationally then the Luftwaffe switches to London (leaving the debate about exactly why for a much longer other time). In ITTL you have had cities in the US bombed in retaliation for Hong Kong, considering how the US population freaked OTL over a U-Boat shelling oil depots and these attacks are coming from the countries next door, I would have thought political necessity would mean diverting strike resources from supporting the ground forces to retaliate against cities would be unavoidable. Think debate over the resources sent to bomber command and the utility or lack thereof of the strategic air campaign until they started hitting the logistic networks and synthetic oil plants (sbipers and we shall reap the whirlwind really is an excellent timeline incidentally).