Withdrawal from Romania and Bulgaria would effectively cede control of the Black Sea over to Russia. Turkey would still have influence, but they are not the most supportive NATO ally.
I had not thought of that. That does present an interesting wrinkle on things. If Putin could get from Turkey a guarantee of free passage for Russian ships through the Bosphorus, then it might make getting control over Romania and Bulgaria attractive. If he can also get effective control over Ukraine, then he effectively locks in control of the entire Western coast of the Black Sea.
That might actually be more attractive than trying to get control of the Baltic states and access to the Baltic Sea, since access to the North Sea would still be subject to potential attack by NATO via Denmark and Sweden.
Lots of chess pieces moving around on this board.
I don't think Hiden' Biden is up to the challenge.