Per the Soviet 1926 Census, there were 350,000 people in Crimea (the Crimean ASSR within the Russian SFSR). I wasn't able to find ethnic data, but a large portion would have been Crimean Tatars, with Ukrainians, Russians, and a few Jews (there were 20,000 Jews in Simferopol, I couldn't find numbers for the Republic as a whole) mixed in. In the same census, there were 2,600,000 Jews (in the whole Union). Forced relocation of even a fifth of the Jews in the USSR would make Crimea a strong majority Jewish (though there might be a scoonch of starvation in the short term). Also, the USSR had absolutely no problem force-relocating all the Crimean Tatars after WWII; then, it was "in punishment for collaboration with Nazis", but I'm sure that something else could be come up with - for example, mass starvation killed half the people in Tatarstan by 1922; the Soviet leadership may decide to "top-up" the place with Crimean Tatars instead of/in addition to Russians.
Crazy? Sure. Almost impossible? Naw. Soviets did crazier stuff.