There's been a power shift in the NHL's Western Conference over the past few years, though I think perceptions have been slow to catch up to reality. For the past decade, the Red Wings and Avalanche (and to a lesser extent, the Dallas Stars) have loomed large over the conference, but the last three Stanley Cup finalists to come out of the west have been Edmonton, Calgary, and Anaheim. The Big Two are really a thing of the past, and so is the rivalry.
Oh, Avalanche-Red Wings games are still going to be events, but without the conference-shaking importance they once had. I doubt the Avs will make the playoffs this season, and while some seem to think signing Dominik Hasek makes the Red Wings prohibitive Cup favorites, there are also some people who think that the earth is flat.
Neither team has dealt much with large-scale failure over the past decade, but this could be the year. The Avalanche have two moderately-large cap spots taken up by players who are ready for the glue factory, Brisebois and Turgeon; the core of the Red Wings' defense has a combined age of deceased. Detroit's offseason signings trump the Avalanche (Hasek and Markov > Klee and Arnason -- actually, just about anything > Klee and Arnason), but the Wings had a big chunk of their emotional core taken away this summer.
I don't see the enmity between the two teams leaving any time soon -- Detroit fans will continue to be inordinately angry that Colorado is allowed to exist, and Avalanche fans will continue to make fun of people who have to live in Detroit.¹ But really, what's the last really memorable Avs-Wings matchup? 2002?
There's still a large part of my hockey soul that's thinking in terms of late '90s/early '00s, but looking at the Western Conference, there's a bunch of teams more exciting than the two grandees -- Nashville, Anaheim, San Jose, Calgary, even Vancouver and Minnesota. I could be wrong about this, sure -- Arnason and Leopold could make people forget Forsberg and Blake, or Hasek could find himself physically and spiritually cleansed and go 82-0. But I don't think so. The Colorado-Detroit rivalry is still going to be fun, but really, at this point they're the two old men sitting on the porch of the nursing home, arguing over something long ago, while the young guys chase girls around outside.
¹ Well, I will, anyway.