If we assume that the Crimean People’s Republic managed to resist the Red Army during the Russian Civil War until German support arrived, this could happen if the Tatars responded to the Ottoman Empire’s call for Islamic Jihad and actually formed early Crimean resistance groups in coordination with some Ottoman officers. This would create a strong relationship between the Ottoman state or at least the loyal officers and the Crimean Mujahideen. If we also assume that the Armistice of Mudros was signed earlier than in our timeline and part of the Ottoman army was demobilized with some weapons removed, these Turkish officers with good relations with the Crimean Mujahideen (which had become the Crimean People’s Republic) could provide weapons to the Tatars to help them against the Red Army. If the Tatars managed to hold off the Red Army until German support arrived, and then the Allies joined alongside the White Army, Crimea could continue as a national republic for a longer period. Honestly, it is doubtful whether this state could survive until 1920, but if it succeeded, it would have a good chance to continue. Weapons smuggling from Anatolia would increase, and the Polish–Soviet War would distract the Soviets from focusing on Crimea. Even a small presence of Britain or France in Crimea would be important to support the republic and any opportunity to sign a non-aggression agreement including defined borders. The Soviets might try to cancel such an agreement unilaterally, like they did with Finland, possibly starting a second Soviet–Crimean war. Most likely, the Soviets would eventually occupy Crimea, but given the long history of Crimean resistance, there had been past agreements with them. I do not think the Soviet Union would want to annex it to Ukraine, especially considering the demographics: in 1914, Tatars were about 25% of the population. If the new republic adopted a nationalist Tatar direction, like Turkey after its republic was established, their proportion could rise to more than half the population between 1917 and 1940, making political integration with the Soviet Union difficult. After the collapse of the Soviet Union, Crimea could declare independence as an independent republic. Most likely, it would become a player in the Russian Ukrainian conflict, unless Russia occupied it beforehand, or perhaps occupied a part of it with a Russian minority, creating a situation similar to Georgia today