I like that this is coming to the movie medium, as it was a great book, but I would have rather seen someone like Jason Blum/Universal doing it. Clearly Warners knows the value of the King trademark and is serious about it, but Blumhouse seems to have such momentum behind it. At least a major studio is attached (imagine if Lionsgate was handling this?).
Here's what I hope for. Add some more rules, or change some of them. As an example, maybe have rest periods of thirty minutes here and there and use that as a springboard for ideas (been a long time, but I don't think that was in the book). Have it set roughly in the near future, not too far into the future (can't recall what the time period was in the book, nor all the rules, assuming there were more than what I was reminded of by the linked Deadline article), so social media can have a big part. Maybe have the Walk be a reaction to current times. Maybe have more than one prize winner, like the top three at the end. Have both men and women in the walk (wasn't it just males? I might be wrong on that). If there were females in it, one interesting scene could be a pregnant woman dying on the road while giving birth (or maybe she is dead and still gives birth, a la The Breathing Method!). Just some thoughts...
Main thing is, though, maybe cast it with a lot of stars that get eliminated fairly quickly, a big ensemble that perhaps slots celebrities in for a day's shooting to keep above-the-line costs down. But cast a couple major stars so it might be ambiguous who wins. Too bad Jennifer Lawrence already did that YA franchise, she might have been good in this as the lead...as for other young stars who could be in it, I really can't think of any at the moment. And I'm not sure who The Major should be...definitely might want to try a gender-reversal there, as well...
And lastly, as always, I do hope this is one of those projects in which King financially participates. King's team must have be having a great time brokering all the deals he does participate in...