Star Wars is an awesome film.
I think that when the film was first made it was revolutionary, the idea, graphics, story just blew people away. Because of this fundamental structure to the films, it means that it has stood against the test of time and is still as popular now as it was then.
Star Wars was created by George Lucas with the first film hitting cinema screens on May 25, 1977, Star Wars IV: A New Hope. It was a 
huge blockbuster phenomenon. Two further films were released in 3 year intervals which meant that the whole of the world fell in love with the Star Wars Saga and everything Jedi. Sixteen years later, the first of the prequel films was released and once again 2 more films were released in 3 year intervals. These however were not so popular, still making a lot of money in the box office ($4.49 billion for Clone Wars) they were considered flops.
With The Walt Disney Company purchasing Lucasfilm for $4.05 billion there are promises for further films to be produced and rumours that George Lucas will still be involved within the production. Which I think it very exciting, lets hope Disney is up to the challenge of continuing this fantastic saga.
The franchise however is massive, there are games, television series, home ware, clothes, toys, lego and many more. Children today born over 30 years later from the original film can still identify Darth Vader (he is said to be one of the most iconic characters ever) and a lightsaber. It has had such an impact that is has even influenced religions!
If I could sum it up in one sentence I would say that, Star Wars has stood the test of time because they consistently re-invent the brand, reaching out to new fans using all technology media available. They are keeping it fresh.
(Plus with the current advancements of hologram messages I'm sure Princess Leia will be popping up everywhere.)