That is what I'm looking for at the opening of the film. But I don't think you can make a good story out of Luke playing a defeatist the entire flick, it needs a third act.
The third act of this movie is where I need Luke to realize the Jedi is absolutely necessary-- if not one last time. Luke needs to come full circle on this "wahh no more Jedi, I failed too hard in the past" for this movie to deliver to the hardcore fans.
Some of that may need to carry over into Episode 9. But that would be an ideal arc along with any potential Vader redemption arcs for Reyylo/Kylo.
My guess is Luke sacrifices himself as the last Jedi at some point in the 3rd act, or in Episode 9. He won't necessarily kick any ass, so much as commit seppuku. Luke's death will likely be some form of Obi-Wan callback, which makes sense-- and makes him very much a Jedi for dying in that fashion. After he dies, there may be 1 Jedi left, hence the Last Jedi having dual meaning that is open for interpretation.
Is Luke the last jedi because of his jedi sacrifice? Or is Reyylo the last jedi because she has an awakening after Luke's death and its going to be hinted that she is to start the Jedi up again in future movies? The ultimate movie would hopefully leave that up to the viewer to interpret the meaning of Last Jedi. There is going to be a little "hey wait, which one is the last Jedi?" for the viewers to kind of discuss over it after they have seen the movie.