In fact there are plenty of new cars. New Hyundai&Kia/1970s Russian/1950s American are about equally represented. I think modern Korean and European are close to half of their inventory, Russian are the majority of the second half and American is a distant third. Most of old American are powered by Russian engines, have Russian headlights and so on.
Just wait till the sanctions really lift. The result would be all those old American cars heading for the scrap pile, replaced by Brazilian-model Volkswagens and Fiats. Not sure if you want to see mostly Volkswagen Fox and Fiat Palio models on Havana streets.