Last time I spoke with the nice NASA people (in a meeting, not on the R/T) they said not only will the tour never return but first move was to stop publishing launch times of the orbiters and the second move was to have the entire airspace made into a permanant prohibited zone...it's only restricted at the moment.
The first move has already happened. The second one keeps being mentioned during security meetings.
Really sad about that - I enjoyed the shuttle tour many times...and the passengers loved it.