They just revert back to Russia annexing the Crimea. Again, not something that Ukraine had as part of its territory, but then again Ukraine has been under the control of another country for centuries. That control has been passed around several times, usually be defeat from war with neighbors.
And the citizens of Crimea wanted to be part of Russia, not Ukraine. Just as the citizens in Donbass want.
People who do not want to know the truth, will never know it.