This went out from the Official Star Wars Twitter in France:

https://twitter.com/starwarsfr/status/646036182187556866

“Together, we will destroy the Resistance and the last Jedi.”

The usage in the text specifically means “The final Jedi.” That clears that up for me. The text in English can be a bit ambiguous if it means a specific final Jedi or plurally. Luke Skywalker is the last Jedi in Star Wars: The Force Awakens in case there was any doubt.