All this wouldn't be happening if NATO had accepted Ukraine as a member years ago when they asked to join. Instead NATO and their western leaders tried to placate Putin by turning Ukraine down. Look how that's turning out. Shades of Neville Chamberlaine and "Peace in our time".
Russia will invade Ukraine if they can't get what they want by intimidation and negotiation. You can take that to the bank. Economic sanctions won't deter Vlad the Impaler in the slightest. He laughs at them. Our KGB spy wants to return Russia to the glory days of the Soviet Union, territorial wise. I'm sure he has wet dreams about that.
Even if they checked all the boxes to be eligible, what exactly is the military benefit to NATO adding Ukraine to the roster other than saying a giant f*** you to Putin and pissing off the Russians even more than they are now? Seems like it just adds one more country to the list that needs NATO (US) protection. And if Ukraine did check all the boxes, they would be a military and economic powerhouse and a net contributor, not a net detriment to any alliance. In other words, they'd be fine without NATO.
The present situation itself is in no small part due to the Russians deep fear of NATO expanding to its doorstep (which it has) when its own power has been on the decline for decades. But they expanded to their doorstep 20 years ago, so why are they all up in arms about it now? Domestic politics more than anything. If you look at the timing of that first stampede to NATO post USSR breakup it coincided with Putin driving an army through Chechnya. The next batch were only a few years later. They have tasted Russian rule & they don't want another helping. And that being said, those NATO admissions were more political decisions than military.
Militarily speaking also, I would think invasion is imminent. Why go through all this if you have no intention to invade. Putin has other easier options to exact concessions. He could have easily armed 80,000 Donbas troops to make life miserable for Kiev and would not have such political baggage.
And any concessions the West gives will be closely watched by China in regards to Taiwan. That's another angle of why the US needs to hold its ground and arm the shit out of the Ukrainians in order to inflict a massive cost if Putin wants invade Ukraine. They need to know and see it's going to really really hurt to invade.