ELI5 Latin - why did such a popular language like Latin die out?

How do French words like “cul-de-sac” and “hors d'oeuvres“ end up part of the English language without being translated to English words? Why did a language as widely spoken as Latin completely die? Why does this 'dead' language still have such a powerful presence in modern English? What is a calque? Why do some Latin phrases remain untranslated in common usage, like "status quo," "vice versa"? 
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