That assumes that the situation will last 50 years. Cuba has been embargoed by the US for so long because its oligarchs all moved to Florida and Texas and took their money with them and have bought themselves some American democracy with it. My cynical side thinks that the worst case scenario (short of nukes or full-scale WWIII) where Russia essentially annexes Ukraine like China did Tibet will eventually lead to roughly the same consequences for Russia that the Chinese annexation of Tibet did for China.