I agree with what you are saying but i still think its best to wait for a trailer before making any sort of assumptions as we have no idea how this will be marketed. Im assuming you've read the books therefore know more of what to expect however I dont believe Dune is a well known enough property that it could hinder its performance. This movie has the best release date you can get and if its advertised as a visually striking space fantasy that pulls in a large enough audience for its OW it's potential is huge.
As for the lack of notable stars, films that try immersing you into a new world work better without them as a distraction. Sam Worthington being a nobody helped for Avatar, giving the audience the feel of something new rather than being 'that new Matt Damon movie'. LOTR, HP, Marvel, Star Wars, Star Trek...These franchises didn't use well know movie stars, they created them and there's enough young talent on board for it to potentially happen again.
Im not saying this film is destined to be huge but I won't write it off this far out just because others failed in the past.