I highly doubt that Cyan has anything planned, unless that TV deal goes through, but we've been down that road before with this (more than once!), and I'm not exactly optimistic about it. Cyan has had a long time to do something with Myst since the last game, and other than maintain the Uru server with fan donations, they haven't done anything. They could have easily done another Myst game instead of Obduction, but they decided to create something new, rather than go with an idea that's over 20 years old (wow, that makes me feel old).
Don't get me wrong, I would absolutely love a new Myst game, site, show, whatever! Myst is by far my favorite game franchise of all time. I just don't really see much of anything happening at this point.