My biggest concern with not supporting Ukraine is two fold:
1. Putin decides that yeah, Ukraine is now his, so Poland or the Baltic States should return to the fold because the world won't try to do anything about it. That would kick off World War III.
2. China, emboldened by US/NATO inactivity, decides the time is ripe to grab Taiwan. Hello World War III.
China is also getting a front seat view of just how effective Western weapons systems are, as well, and how badly the supposedly "second most powerful military in the world," is being handled by a much smaller nation armed with those weapons that I really think it has cooled some of their expansionist ardor.
A few days ago I read a very interesting, but rather horrifying, short story by Jack London. Written in 1910, the Unparalleled Invasion recounts the rise of China. First Japan, after the Russo-Japanese war attempts to invade China and is beaten into submission, never rising to become the world power that it did in the 1920s through 1940s.
Then China begins semi-passively invading other nations and spreading out and, essentially, becomes an unstoppable force.
Until a scientist in the United States comes up with a plan, and the rest of the world signs on.
Essentially, the world unites to cordon off China both on land and at sea and then overflies the nation and institutes unrestricted biological warfare. Plague, anthrax, yellow fever, etc., are dropped on China, killing hundreds of millions and causing an almost complete collapse of the Chinese economy and civilization.
Really, really *expletive deleted*ed up when you think about it, and highly indicative of the burgeoning fear of "The Yellow Peril" that was rising at that time.
