This is going to be implemented in Sitefinity 4.0 for sure. We have it in our ToDo.
For the moment, you can add additional properties to the pages, as showed in this blog post - http://sitefinity.habaneros.com/default/09-02-17/Page_Meta_Data_-_Intercepting_Sitefinity-769469583.aspx
Then you can create a timer classes which change the ShowInNavigation property if the page is not published anymore.
Hope this helps.
the Telerik team