I hate to correct you, but as someone who's actually seen a script for the final episode, The End of the Line, there is no mention of the cure being found in it. It is true, however, that the entire series of Crusade wouldn't be devoted to finding the cure, which would be found sometime during season two, but would reveal a conspiracy in Earth Force to develop Shadow technology. The idea in season two is, no one would believe the crew of the Excalibur that something bad was happening back home, and eventually, they would have to pull a Sheridan and take on their own people. What's more, we would have also discovered that Techno-Mage technology is based on Shadow technology. This would lead to Gideon distrusting Galen, who is clear from later scripts to have a secret agenda.
What is more annoying is the fact Bester was due to return in Crusade, but never got a chance to, as the series was canceled before his episode was filmed.