IMAX confirms that Denis Villeneuve's Dune 3 is to release in 2026, though there might be a question mark over its Dune: Messiah title...
If you download this PDF report from the Q2 2024 IMAX Investor Presentation, there are charts showing which films are being produced with IMAX in mind all the way through to the end of 2026.
He did adjust the story in Dune 2 to better align with Dune: Messiah but it also shows he is no respecter of the original stories, so he might still take things in a different direction, especially as Messiah is, in some ways a darker reaction to the success of Dune and it is unclear how well that would translate into a blockbuster movie. However, it may be Villeneuve has the confidence of the studios and will be given the room to make an... "anti-blockbuster".
Maybe he'll try to combine the next two together? I haven't finished Messiah yet or finished the third one, but I heard it makes a good trilogy?