I don't think that rivalry is meant that way in soccer. They were competitors in the 90s and now with Dortmund's resurgence they are competitors now again. You don't go from being a rival to not based on form, just like Borussia Mon weren't Bayern's rivals in the 70s they won a lot and were Bayern's toughest competitor and unlike a rivalry once BM faded no one took a second glance when these two teams played against each other. Just like Barca and Athletico aren't rivals now even though they won the league against each other and knocked each other out of cup competitions, you don't see people going crazy over villa or Arda like they would a celtic player going to Ranger or someone who still gets hate on this forum(Figo). They are tough sporting competitors recently, just like Bayern Dortmund. Its nothing like Barca real, there are deeper reason for those animosities and other rivalries of which Dortmund actually has one, schalke.
I get your point but the way rivalries develop in the first place is based on the ability to actually compete with each other and being more or less on eye level.
Take the Dortmund - Schalke rivalry for example, which in Germany is often named the Mother of all Derbys:
The Ruhr area has a high density of football clubs, and as such there are a lot of local derbys, where Dortmund-Schalke is just one of many. Contrary to the Old Firm or El Superclasico the rivalry between Dortmund and Schalke is relatively young and actually quite non-violent as far as the fans are concerned.
The histories of both clubs aren't too different from each other either: Both clubs originated in worker districts and both clubs served an integrative function for immigrants from Poland and East-Prussia. There are no religious or ideological conflicts between these two clubs either. And Anno 2016, fans of both clubs pride themselves to be a symbol of the heart and passion of the Ruhr area still.
The actual rivalry between these two clubs originates from something different: Schalke was the favourite team of the Nazis and as such received a lot of backing from the government. They were the top dog of their league (Bundesliga didn't exist yet) in these days and could not be realistically challenged.
After the second World War, in the era of the Oberliga West, Dortmund became an actual contender for winning the league, and they did three times after 1947 and took over Schalke in the "Ewige Tabelle" (all-time table).
These years are the root of the rivalry.
And that's my point: This rivalry, and many others, originate from two teams being able to compete with each other on the sportive level and one team challenging the supremacy of the other. And on those grounds, Dortmund-Bayern can be classed a rivalry as well. It's just more recent.
You're completely right in that this doesn't equal Barca-Real at all. Because that rivalry has political, cultural, economical and historical backgrounds that fuel it. But this appears to me rather as the exception than the norm. Dortmund - Bayern, at the very least, is a rivalry in the making.
Well its not historical at all. That their game doesn't even have a special name like el classico or rivierderby but is rather just referred to as bayern vs dortmund is a big clue to that. But you and others feel that one is developing and has something deeper behind it other then simply sportive reasons. You mention class rivalry which definitely is a part of other soccer club rivalries but isn't that usually specifically for same city rivals? Wouldn't fan bases need to interact with each other fairly often in order for clubs to translate class strife like river plate- boca, inter-ac, the barca clubs? I can't think of any cross town major rivalries based primarily on that reason, how often would an upper class Munich dweller meet a working class Dortmund fan for any real animosity to develop?
Same as above basically, and as I said, supporters on both sides of the fence blow it out of proportion. Add the media and DFB/DFL to that who'd love to have their equivalent of el Clasico for reasons of cross-border-marketing of the league. The media actually also gave it a name: Der Klassiker. So there's fair share of astroturfing in this entire thing going on as well.
As for the class strife thing, that's more or less incidental between these two clubs as the rivalry is based on sportive competition, and it's also somewhat of a stereotype: In reality, both clubs have fans in all social levels. It's also not directly articulated too often for the reasons you named but it's something that lingers unspoken in the background. When it's articulated as such, it is not so much a class issue but a passion vs. money issue.
Its interesting you say that about dortmund fans view of Bayern Munich stadium atmosphere. i have only been watching Bayern recently but I haven't found that at all to be their in stadium atmosphere. What you are describing sounds like Real Madrid's atmosphere. they will whistle their team and boo at halftime even 0-0 if the fans feel they are playing boring. Bayern's from what i've seen is like Barcelona in that regard, very even tempered. Its just that where Barcelona is quiet with graveyard silence Bayern actually has ultras who keep it moderately loud with nonstop positive chanting.
What Hummel's said can be viewed as hypocritical but so many people are wrongly trying to paint this as something like the Figo transfer and pretending that these clubs are rivals when they aren't.
In my opinion, the atmosphere in the stadiums of the elite-of-the-elite clubs depends majorly on the stakes. And in 95 % of matches, the stakes for these clubs are virtually zero. Bayern had an overwhelming atmosphere in the second leg vs Atletico, but so did Barca in their first leg against them, especially when Barca began to put Atletico's box under siege, because everyone could feel that this is an opponent that can blow their club's lights out.
The atmosphere in Bayern's stadium in particular is indeed quite underrated and better than it's reputation, plus there are the Ultras of course. But these are about 600 people plus another 600 people who cheer depending on the situation and that's nothing compared to Dortmund's Süd.
And this thing is again a facet of the passion vs. money issue, hence #echteliebe.
Hummels transfer indeed doesn't equal the Figo transfer for reasons stated above but there is a rivalry between these clubs and Dortmund fans have every right to view this move as treacherous. This thorn runs deep for the fanbase not only because of his hypocritical statements but also because many sincerely believed Mats to be one of the last football romantics in the game. He isn't, and truth hurts.
Good post btw., you should get yourself an avatar so your posts are easier to recognize when scroling through.