Greek has been with us as Christians forever, and it will always be so. The New Testament is written in Koine, the common dialect of Greek. While most of our liturgical language is inherited from Latin, we will always have the Greek "Kyrie" as part of our liturgical lives.
In addition, certain Greek letters have keep their place in our liturgy: the alpha and omega placed on the Paschal Candle; the chi-rho, a monogram for Christ; and less well know, the Greek letters mu and psi that may be blown on the face of the waters when blessing them for a font.
Indeed, Greek is here to stay.
