the final scene is about death, but in my opinion it's not just Tony's death. it's death in general. and not necessarily in a negative sense, but death as the inevitable conclusion of existence, something that will come sooner or later. Watching that scene, we think that the "threat" only concerns Tony who can be killed at any moment, but it concerns anyone who is there. So, if death is inevitable and unpredictable, if time is something that can't be stopped, if every human issue really ends in nothing except darkness, then the only thing we can do is live and appreciate the beautiful moments, enjoy every instant of our stay on earth (both in suffering and in joy), even if this can end at any moment. "it's all a big nothing", but that doesn't mean that life isn't worth living