No going to happen. If Ukraine controls Zapharizhia and Kherson, and the Kirch bridge is down. Russia will have no choice but to surrender Crimea. They cannot hold it under those conditions and Ukraine has no incentive to let them.
How did the US do after it ignored red lines from China in the Korean War?
China’s industrial economy has grown massively since then, while the US has shut down factories and moved them overseas. If the US can’t keep up with supplying weapons to Ukraine, it would be buried in a direct conflict with China.
The US stopped being the arsenal of democracy decades ago.
Ben Rhodes relates an anecdote where the Australian PM pointed out to him that the European collapse lead directly to America getting pulled into WWII.
While it is true that Japan and the U.S. were beefing about Manchuria, it was limited to sanctions on war material. But then opportunity opened up in French Indo-China (ceded by Vichy), Dutch East Indies, Hong Kong, Singapore, etc, etc, etc. And of course Pearl Harbor was then bombed
-during a state of peace-to forestall American intervention.
The point: European Problems tend to spill over. The French-Indian War, the War of 1812, The Quasi War, The War of 1812, The Barbary War, WWI, WWII, Spanish-American War, Haiti: all examples of European mischief that pulled America in.
While Rand is privately owned, it is arguably the strategic brains for the US military-industrial complex. Rand originated as an Air Force program at the end of WW2 before it was spun off in 1948. Most of its funding comes from federal agencies that are directly responsible for the military and national security.