I've been around a long time, and I love Myth more than reality. However, I feel that a Myth III would be an utter dissapointment. How could you possibly continue this story without ruining all that has come before? Chimera was perfect; not a continuation but an offshoot (or extension if you will) of the original story.
I personally think that the Myth community should disparage any thoughts of a Myth III (I might be alone in this, I know). We have been making maps, extensions, and conversions for quite some time now. While I do think that Take Two should allow those that are more familiar with the story to help with any additional story lines and/or design, I do not think that a third installment will be beneficial to our dillusion. There are many side stories of Myth I & II that could be told. Let's promote that.
Zandervix