Germany/Austria in 1939 is a completely different case.

Let's take a look at the ethnic groups in Crimea - 2014 census:

Russians - 65%

Ukrainians - 15%

Crimean Tatars - 11%

Please note that, of the 15% of Ukrainians living there, most (60%) speak Russian as their first language.

We may argue if the 97% referendum result was rigged or not - we may never know.

But based on the above numbers I think that the people in Crimea really prefer to be part of Russia - because they are Russian!

https://en.wikipedia.org/wiki/Demographics_of_Crimea