QUESTION: Is it possible that the light of the stars that we see today,
doesn't exist
anymore, because the star also doesn't exist, in function that the light
takes millions of years to come the Earth? 
ANSWER from Dave Zurek on March 25, 1996:

Astronomers don't think that stars cease to exist in the time that it takes 
the light to get to earth but a star may have gotten fainter or brighter 
since the light left it. We see stars all the time that get brighter and 
fainter. In fact there are many stars that seem to appear from nowhere and 
then fade to the point where we cann't see them anymore. It is true that 
because these stars are so far away that the brightening and fading occured 
many years ago though we are just seeing it now.

I hope this answers your question.