A very good question best answered in the item below. It just is not dead. Languages do devolve into dialects, but always retain their core vocabulary while shifting sounds somewhat. It took public radio to recenter English everywhere from this phenoena.
English is actually an unusual hybrid of the two core languages of Latin and German and both are Indo European derived with much in common with Sanskrit. Sanskrit has deeper roots than any..
Thus Latin is today archaic versions of several modern dialects of Latin. Recall also that written Latin changed seriously during roman times as well.