I see the biggest challenge as keeping the audience engaged long enough.
That said, what about as an animated series? You'd could still get big name talent at a fraction of the cost.
I see your point but I just don't see it as an animated series.
Yeah, I think an animated series would be a VERY hard sell. Animation is still seen in the west as mostly for kids and Dune is obviously not appropriate. Plus, despite what people seem to think *good* CG animation is very expensive for any weekly series. Clone Wars pulled it off because Lucasfilm has very deep pockets and a direct revenue stream via full control of the merchandising rights.
Honestly, I can't see a live action Dune series costing all that much more to produce than GoT. They'd both have lavish sets, CG matt paintings for cites, set extension and the like, a lot of custom made costumes and CG creature effects. The only real difference is that the filming locations would have to look credible as the deep desert. As in NOTHING but sand as far as the eye can see. Digital grading can make things look hotter and more arid (Dune's sky is supposed to be silvery instead of blue for example) but you still need the steep dunes.
Mind you, most of the book takes place indoors with only a few big set pieces (VFX wise) spread out across what would be three seasons. The spice harvester/worm attack, the fall of Arakeen & flight into the desert, Paul's worm riding trial and the final battle of Arakeen. Everything else is pretty straight forwards. Indeed like in GoT they'd probably have to add in more action in places to keep people interested.
It's still expensive, but these days it's very doable and if it becomes a hit, even profitable. As with all things though it comes down to the execution. It'd need a very talented showrunner, a team of competent writers and directors and one hell of a cast.
...Also, Bryan Cranston as the Baron....or Shaddam....Or Thufir. Point is, he has to be in there some where.
