Source? Because with out that, all you've got is the same rumors that have been floating around since 2004. I'm pretty sure they said at the time that the fourth movie was going to be the last one at, too.
The series isn't even running in reruns anymore, so I wonder if it's got enough popularity left to merit a new series. Besides all of that, I have heard (though I admit I didn't read it) that even the manga had kind of an open ending, anyhow.