Ukraine doesn’t need to surrender. Even if Russia succeeds its initial military objectives, they will need to maintain an occupying force that will almost certainly face a determined Ukrainian insurgency.
At this point, NATO needn’t get involved. Russia has succeeded in pushing NATO members to increase defence spending as well as pushing neutral states such as Sweden and Finland towards joining NATO after the war. All the while, the Russian economy looks like it’s going to tank.
At this point, it seems like Russia has made a blunder geopolitically.