Interesting, didn't think this would happen! I'm guessing it might have something to do with the abandoned movie concept.
However, I don't have a ton of faith in this, to be honest. Until we get a trailer or plot synopsis. Right now they could be doing anything with it, from something that's super faithful (Which wouldn't necessarily be a good thing) to something like turning it into a "young adult"/teen romance flick (potential is there with Book of Tiana), which wouldn't necessarily be a good thing either. I think the best service to the spirit and point of Myst would be a show about a cast ending up on a mysterious island that had all sorts of mystery about it, but LOST did that pretty well already. So we'll see.
If it sounds like I'm being really negative, I'm not trying to be, but this is one of those franchises that has a style, characters, and ideas very specific to the gaming scene, so they'll need to re-write a lot of it. So my hope is that they don't turn the source material into something it's not, but also that they aren't too afraid to deviate from that material in order to make the best show possible.
The game aspect intrigues me a lot. I wonder if it's going to be an actual adventure game or if its going to be more like the mobile games we see now.