Re:
Hard to say of course, but I can't imagine it would have been the end of manned space flight, or even the Shuttle.
If you look at the experiences of Apollo 1 and Challenger, we might expect a similar mode of reaction. It may have taken five years, but NASA would have probably done a re-design on the TPS, and many other systems, with the result being a better Orbiter.
Ronald Reagan was President at the time, and I just can't see him ending the Manned Space Flight Program.