Likely not, Ukraine is a democracy (unlike Russia, which is Putin's autocracy). Even if such an event happens, next in the line will take the lead, and even more anger will emerge among people. Ukrainians are defending not Zelensky, but their country. In Ukraine the "contry (or rather state)" is not by definition equal to President, like it is in Russia.
I was being realistic - it'll be a puppet - call it as you wish, president or subordinate of Putin. Unless Ukraine could hold the fort against this invasion, and preserve their independence from Moscow, anything else will be a servant of the higher power, by any [other] name.
