That is as long as the writer is fairly well known. From the sound if things, Gabriel Marquez is pretty well known as they had a big tribute of his life Mexico City. That usually means the people in that area our going to make sure is work stays in the lives of future generations.
While I have not yet read any of his work, I did recently purchase Cien Anos de Soledad based solely on the fact that it was "recommended" as one of the finest examples of Spanish Literature. He wrote a large number of well known books, some of which have been made into movies and some of which may yet be. There is no Latino author better recognized outside of the Spanish world and that alone will set him apart and ensure that generations to come will continue to read his writings.
Yes, I do believe that Marquez's writings will last long and make an impact on the readers. His work is mostly based on magical realism and there is not a single writing of him which does not relate to the reality of life to a certain extent. This is the reason why he was regarded as an acclaimed writer and his work will be remembered always.
Marquez will have a lasting impact because he was a unique voice for Colombia, one that covered both fiction and journalism. When very few writers make a splash outside of their own culture or language, an author that wins a highly visible award like the Nobel Prize is likely to remain in the public consciousness, whether it is within his own culture or not.