At any rate, Launius describes a lecture called "Whither the Space Shuttle?":
This presentation reviews the history and legacy of the Space Shuttle program after thirty years. It suggests that while the shuttle was not an unadulterated success, on balance it served a venerable role in spaceflight and deserves an overall positive assessment in history. Additionally, the Space Shuttle provided three decades of significant human spaceflight capability and stretched the nature of what could be accomplished in Earth orbit much beyond anything envisioned previously. Most significantly since the American human spaceflight program has always been focused in national prestige, the Space Shuttle served well as a symbol of American technological verisimilitude. Finally, this presentation discusses the retirement of the Space Shuttle and possibilities for the future of human spaceflight.
If you want a sense of how Launius answers those final questions, check out his earlier posts (here) and (here). He also has an extensive bibliography on the shuttle posted here.