The vast majority of the Crimean population (including the majority ethnic Russians / Ukrainians and the minorities such as Greeks and Germans) don't want to be a part of Ukraine again. Only the minority Crimean Tatars want to secede from Russia. Even if the UN conducts a referendum in Crimea, more than 90% will vote to remain in Crimea.
I have read the reports from western mainstream media. They say that the two majority groups (ethnic Russians and Ukrainians) are happy under the Russian rule. The only group which is opposed to the Russian rule is the Crimean Tatars. Not my opinion. Just quoted from Western media.