As far as the fourth wall goes, it's bullet-proof. Not even a nod to resolution. Tony's life exists outside of the viewers' experience of it. Maybe it was presumptious to assume that a story presented with minimal narrative effect would have an ending that generated closure.
Or was there a cohesive theme to the show? It certainly wasn't the power of psychiatry. As the final season has established, Tony's just been sharpening his teeth. As an anti-hero, Tony walks a line that discourages moral judgements, though his on-screen psychoanalysis pulls the veil back just a little on that. Ultimately, Tony and Dr. Melfi just do the work of first-person narration in written word, without the heavy handed narrator, revealing Tony's internal states and opinions. It's not about the morality of a man and the means he goes to in providing for his family.
It is, put simply, about family. Family is the institution that prevents real change in the individual. One theme that's been consistent throughout the series is the inability of family members to branch out. Tony tried in college and failed, ultimately returning to the mob. Meadow's several attempts have left her a likely mob-wife with paralegal potential. This season, AJ tried to form his own crew, then to become his own man, (in the army) and, in the end, got a job from his dad, making contacts, with plenty of upward mobility. Carmela's several attempts to branch out have been met with resistance by Tony. She's never left him, after all these years. Family prevails, and they get the last word.
Nine years for that? Hah!
Or maybe the fourth wall has a subtle crack in it. All the players that the viewers expected to be in place were there. The FBI agent in the USA cap, the creepy guy going to the bathroom, the group of black guys reminiscent of the first hit on Tony all those years ago, Meadow arriving late and almost getting hit by a truck. Something to consider: a lot can happen in the thirty seconds of black silence between the last scene and the credits. A choose-your-own-adventure? Fuck that.