So that's how you planned to do it, Mr. Kripke. Well done, I say. From the opening moments of "Swan Song" — in which we learned about the history of Dean Winchester's Impala, beginning with it's 1967 build date at the GM factory — to the episode's final denouement, you gave us more or less the Supernatural finale you promised, as Sam Winchester submitted to the Devil, knowing full well that the odds were against him and the situation was grim.

Knowing that no matter how many gallons of demon blood he chug-a-lugged, no matter how many bars of Kansas played in the background, his power would never be a match for Lucifer.

Or would it?

Again — just when we thought we would be left dangling on the precipice of Hell — the last scene of your finale threw a monkey in the wrench. Was that Sam watching Dean reluctantly doing the "domestic thang" after the younger brother won a surprise victory over Beelzebub? Or did Lucifer manage to gain the upper hand, unbox himself and is now headed after Dean, perhaps next season eventually giving us the powerhouse showdown between the two brothers that was foretold? After all, the Devil is much too much fun a character to kick to the curb after just a few episodes, right?

Either way, it hints that unfinished business will be the order of the day when the series returns, because even if Sam is Sam, he's doubtless been changed irrevocably by his experience.

There were so many moments of sheer intensity in "Swan Song", it's difficult to list them all. Chief on the roster for this reviewer was Sam making Dean promise not to try to bring him back if Sam could successfully shackle Lucifer down under (Hell, folks, not Oz). "Go find Lisa, pray she’s dumb enough to take you in, go to barbecues and football games," Sam urges his older brother. "You go live some normal, apple pie life, Dean."

After all they'd been through together, it was a heart-wrenching emotional moment.

Of course, when you go toe-to-toe with the Devil, you expect certain things: a few examples of him wielding mind-blowing power; lies & duplicity; and, of course, the unexpected. "Swan Song" offered all three; next on the roster of great moments in this episode. The final battle between Lucifer/Sam and Michael/Adam was elegant in its simplicity, yet terrifying in its execution. Lucifer/Sam shows Dean no mercy when the elder Winchester decides to crash the cage match of the millennium. Lucifer/Sam beats Dean practically to a pulp, with Dean looking like Mr. Balboa at the end of Rocky. Dean just takes it, fervently hoping that some remnant of Sam remains in his brother's hijacked husk. Fortunately, it does. It apparently just needed a trigger—one set off by powerful family memories (a mainstay of the series' mythology).

Dean gets off relatively light. The same cannot be said for Castiel, whose choice to incinerate Michael/Adam before the final confrontation can take place gets him blasted into ground chuck with a lazy wave of Sam/Lucifer's hand. An example of absolute power corrupted absolutely, and a "helluva" scene.

Sadly, Bobby doesn't fare much better, as the Devil snaps his neck with the flick of a wrist (and after Bobby had just gotten his legs back, too).

With Cas and Bobby dead, and Dean about to be turned into organic pulp, I felt a twinge of genuine melancholy. Here was the deliciously nasty Devil we all finally hoped would emerge…and in Sam's body. Yet for an instant, Mr. Kripke, I began to feel a bit sick to my stomach—I really thought you were going to go all the way, have Lucifer/Sam dispatch Dean once and for all, and then show us glimpses of the final Apocalypse. I could feel that dread, even though I knew it couldn't happen, because it would be too much of a downer ending, this is television, and we all know that another season is coming.

Yet despite that awareness, you really did take me right to the edge dramatically, and I commend you for a deft bit of writing.

Of course, all of this brings me back to where I began—at the end. Dean is alive and honors Sam's request by exploring the suburban Leave it to Beaver lifestyle; Cas gets reassembled with a little assistance from the almighty (and perhaps some Hamburger Helper), then reanimates Bobby; and Sam has supposedly boxed Lucifer in the netherworld...

...until the very last moment of the very last scene.

The wayward sons look set to carry on. But under what circumstances, and in what form?

We'll all find out in Season 6. Meanwhile, feel free to debate the meaning and ending of "Swan Song" below. We might even join you.