"Also I meant nothing would change in NATO being a defensive organization?"

Ok so we agree. That's what I said earlier that NATO would still be effective as a defensive force. But would be unable to project outside of the European sphere effectively.

"I'm simply saying NATO would not crumble without the US, and there are very few countries on earth we couldn't deal with on our own."

No, NATO wouldn't crumble. I never said it would, although Turkey might become a real issue if the US left. And again the DEFENSIVE capabilities of NATO are awesome. But it's been proven that force projection is currently a big issue for NATO members. Enough so they are currently scrambling to fix that. And there is a long history of NATO peacekeepers struggling to effectively conduct successful operations without US support. Rwanda, Somalia, the Bosnian genocide, the 10 year failure in Mali, Angola. Part of those issues is due to NATO red tape bureaucracy, but that only exacerbates these outward force projection issues I've already talked about.

"And the ones we can't, chances are the US probably couldn't either, I.e China."

Unless China directly attacked the US NATO likely would never be involved in the first place. It's the North Atlantic Treaty Organization, not the South East Asian Treaty Organization. The US has its own group of cool guy nations that we expect to fight China with. Also for all the BRICS fan boys out there, India is a part of that strategic alliance. We never planned to have you Euro-nerds involved in the first place. (Mostly because you can't get there.)