One of the reasons of not granting NATO membership was indeed in fear of russian retaliation. Russia took Crimea and invaded Donbas since then even without the membership promise. Putin is already upset so no reason not to bestow the membership on Ukraine.

Kicking out Russia is next to impossible as they’ve dug in. What Ukraine has in superior weaponry, Russia has in numbers. Time is bad for both parties, but worse for Ukraine, as Western fatigue will inevitably come.