I'd love to see a musical version of Holes, as long it maintains the sophistication of the story and doesn't go the route of Be More Chill & Lightning Thief.
I didn't know Sachar adapted it into a play. It's interesting to me because I think the show could really work beautifully if it was musicalized, but I don't necessarily think the stage is the optimal medium for it. This isn't necessarily to say that they should make a movie musical, or that the play is bad (I've never seen it). I guess I just feel like, the medium of live theatre doesn't seem to have a lot to offer to this already-flawless story, unless it were to be musicalized, so I'm surprised it was adapted as a non-musical.
And I don't say that lightly - I think the mentality of "every stage adaptation of a well-known property has to be a musical" is idiotic and has led to tons of inert, lifeless, boring musicals that might have made decent plays. But in this case, with this material, I feel like musicalization would be the best way to do it onstage.
Let's hope it still happens someday, and please, for the love of God, give the project to someone with imagination and depth, and keep it far away from the likes of Stephen Brackett, Joe Tracz, Joe Iconic, Pasek & Paul, etc. etc.