I watched this when it first came out and remembered really liking it a lot. I just went back and watched it again over the last month or so. I didn't even recall that it kept going after Light and L concluded. Totally blocked out that part of the show. I don't know how you keep that and do this show in 1 movie. It would be insanely rushed. I have hope that its ok, Willem Dafoe is a great casting choice for Ryuk. However, even though Ryuk is a pretty iconic symbol in the show it's not about him. I hope they pull it off because the first Act if you want to call it that is phenomenal and I think could really do well as a movie, but knowing the history anime has turned into live action movies, I have the lowest of low expectations.
The only hope is that it's being done by Netflix, and they have really done a very good job on most things they've done so far