Yeah, I'll concede. We can all agree that it depends on what works for the times, and things change, develop, degenerate, and resurface. Each legitimate religion should have all three factors at their core: Birth, Death, and Sacrifice. As far as the relation of myths to empirical science, I guess I'm easily convinced by some pretty redundant mysteries. Ancient civilizations are especially interesting, with the most obvious example being the pyramids, but also artwork depicting flying machines, extraterrestrials, and other incredible ideas.
Theorizing about it is a major time sink and waste of effort, but if people are experiencing the internal worlds on a regular basis through spiritual, devotional means, and meanwhile empirical science is discovering more and more about the 4th coordinate through the work of brilliant physicists, hopefully there will be a day when experts find some common ground and agree on some things. We'll probably see an even bigger flame war between sections of humanity though, as people will disagree merely about semantics.
Briefly touching on Nirvana though, several schools that teach synthesis discuss two possible paths for somebody reaching a level of mastery where they can choose the infinite bliss of Nirvana, and opt out, like you say, and disappear from existence rather than live nearly endless amount of physical incarnations. There is also the path of the bodhisattva, where one renounces nirvana to keep working on behalf of humanity and suffer immensely. I'll stop overgeneralizing things and being so dramatic. We do what works for us until the end. Even eternity has an end. We're not even a spec on a pale blue dot afterall.