This is an illusion, and a very dangerous one for all parties.
Ukraine will not be able to regain Crimea under any circumstances, since Russia's nuclear doctrine
states that it will use nuclear weapons if the Kremlin decides that the existence of the state will be threatened.
A few months ago we all thought we'd be waking up to news of Zelensky dead and Kyiev occupied by Russian forces. At the time, Russian failure and retreat within a few weeks seemed much less likely than Ukraine ultimately regaining some of it's land that was seized in 2014 today.