There's is no NATO without the US, it would need to be something else and function differently. That takes years because there's too many countries involved. We would likely get two military unions in EU - North and South, North on helping Ukraine and South trying to distance itself. Furthermore the time is running out until this grows into a bigger conflict, this is just from couple of days ago: "Alarm in Denmark after Russian ship fires at military helicopter"
It's possible the conflict will get bigger, but I doubt it. I think what's happening right now is all about internal Russian politics. The Russians will lose in Ukraine without a big influx of new troops, something that's very unpopular. By provoking his neighbors in a few highly publicized incidents, Putin can play into existing Russian paranoia about invasion from the west, which will allow him to conscript another half million men.
But new troops don't help him if the need for troops gets correspondingly larger. My suspicion is after Putin gets his troops most of the talk about a wider war will die down, and all those new resources will be dedicated to Ukraine.
There's is no NATO without the US, it would need to be something else and function differently. That takes years because there's too many countries involved. We would likely get two military unions in EU - North and South, North on helping Ukraine and South trying to distance itself. Furthermore the time is running out until this grows into a bigger conflict, this is just from couple of days ago: "Alarm in Denmark after Russian ship fires at military helicopter"
https://www.politico.eu/article/russian-frigate-fires/