I seem to recall Denis making it clear this is where he intends to stop, for exactly this reason.
goddamnit, I wanted to see
spoiler
Leto 2 becoming the sandworm god
but I guess with some of the disappointing scenes in the 2nd film (Paul taming Shai Hulud, the visions just being shots on a beach) , it probably wasn't going to go down the way I wanted to. It's a shame.
Soundtrack was still awesome, but it did re-use a LOT from the previous film