Putin is prepared for it since Russia has its "friend" to trade with in case US and NATO imposed hard sanctions.
.... I still can't figure out why Putin is doing this.
It's hard to understand him if you're used to western ideologies. He's coming from the "protect Russia from destruction" point of view if you read his translated speech. He's fearful that one day the NATO will choke Russia if Ukraine joins the Alliance. Russia already experienced a blockade in one of its sea routes before and Putin doesn't want a possible repeat of that.
Funny how he also calls the US an empire of lies.
I would also like to add that it seems Putin could not get an assurance that Ukraine will remain a neutral country from diplomatic talks which forced him to go for a military solution.
So before the threat that he is thinking of, he wants to eliminate it in the expense of thousands of lives that will be lost.
Ukraine are now in pro-democracy so I don't think what Putin was thinking will happen. He is too paranoid, in my opinion.
Hopefully, we will see fast resolution of this war. But I believe, Ukraine will surrender as they have no resources to fight Russia.
Russia seems to be very prepared on this attack. So high likely, Putin is planning this for years. And no one can stop him as he already started the war.