Obama at least ended the outright stalemate. That has begun a dialogue. I think that the best policy is to simply let it go. Things will change and we do have a stable dictatorship able to transition into something better without another blood bath.
What will happen is that we will see some Cubans immigrate. We will see plenty of folks visit and even invest. This all facilitates natural change as the old boys all die off.
Applied communism was monstrous. Fidel was hardly unique. And yes, embargos are stupid in quite another manner. They are only useful for short time periods and if not working they must be abandoned. This again opens the door for private dialogue.
We could have been at this point in 1970 when we dropped our embargo of China. It is hard to imagine how the outcome would have been worse in terms of US policy...