Correct; Dune is meant to take place in the far future of our galaxy. Star Wars is a "far away" galaxy and in the distant past. The "long time ago / far away"

Correct; Dune is meant to take place in the far future of our galaxy. Star Wars is a "far away" galaxy and in the distant past. The "long time ago / far away" disclaimer is brilliant in a number of ways, not the least of which is that it helps the viewer suspend disbelief. It's also an elegant way to future-proof the technology, clothing choices, etc., on display in the movie. If Star Wars had made a claim about being the future of our galaxy, it would age pretty badly (the way that the "futuristic" inventions in Star Trek tend not to age well; consumer technology tends to advance more quickly than projections thereof).