They could always be Upper Volta with nukes so it have to fall due to inside pressure. And that is a interesting process. The way I see it, people ask for as much as they are allowed. When the crackdown comes, they get crushed. (As a consequence, I don't really take the word from people living in an dictatorship supporting their goveerment.)
So how long until the opposition bounce back? Some form of will bounce back quickly of course but if the coup-makers acctually manage to pull of the coup, they would have/need better support from the guys with the guns. And hence, they may manage to keep power to present day.
Of course, I dubt they have the power to do somethig good with the economy and want to avoid rocking the boat.