In the late '80s and mid '90s there were several proposals to replace the Space Shuttles with a new, follow-on program incorporating "lessons learned" to (hopefully) achieve the initial goals of the Shuttle program (cheap, reliable space access). (eg., this Langley proposal, X-33, or OSP, all of which had their own approaches) So, the question here is how that could be achieved for real, preferably prior to the *Columbia accident, and what effects having a Shuttle II program started by, say, the late 1990s might have. It seems that it might be interesting if the program is started and going well (ie., not failing terribly like X-33, however unlikely that might seem) when a *Columbia-style disaster hits.