[El Conservador]

¡CUBA no sería LIBRE! ¡mientras VIVA FIDEL!

The correct grammatical way is ¡CUBA no será LIBRE! ¡mientras VIVA FIDEL!

The former implies SUPPOSITION, the latter is an AFFIRMATION.

[Salman]

The notion was "Cuba will never be freed, until (implied)". However you are right, it shoud have been "Cuba will not be free" .

Who knows, maybe Cuba will be freed before Castro dies. Point well taken. I only describe what I did.

[Ax]

Shouldn't it also read "mientras vivE Fidel?"