While I believe a great Dune series could be made, I'm not sure any studio would be willing to put the resources into it needed to make it a worthy film. I just don't see Dune as Summer blockbuster material. Too complex.
That said, Ideally we would see something similar in scope, budget, and skill that was evident in the Lord of the Rings films. Dune would also be wise to follow Jackson's example of releasing extended versions down the road for those who want a more complete vision.
I Love the 1984 film, but I say that as a guy who likes David Lynch more than Dune.
I get that the miniseries is the most complete filmed version, but I've never cared for it. It's just lacking the budget and acting talent to make it very special.