Actually, it is not only the duration of an idea makes it “ultra-conservative”. It is more complicated than that. All those teachings you enumerated were “revolutionary” when they were first uttered. No system outside Christianity ever embraced such puritanical ideas. Today more people than ever reject these ideas, while happily accepting other tenets of Christianity. Maybe you would call them heretics who only subscribe to a watered-down variety of your faith.
But if you don’t like the phrase “ultra-conservative” because of lengthy time implication of it, we can call it “ultra-orthodox”. How about that as a compromise?
Be as it may, those ideas steadily lose ground. More and more Catholics see nothing wrong with contraception, IVF, masturbation, cohabitation or fornication, etc… (adultery should be a different matter, since breaking contracts is not in the same ballpark).
But the existence of the church is not “threatened” by outside forces. If there is any threat, it comes from the lowering attendance and decreasing acceptance of the “super-orthodox” concepts.