Weak. The NFL changes have largely involved overall parity, and were not directly in response to a single team. I think claiming Bayern's 6 run is more dominant than anything else in baseball or NFL is pretty silly. The Packers themselves dominated the league in the 1960's, winning 5 titles in 7 years (pre-merger). The Yankees did almost exactly the same thing in the 1950's and in the 1990's. Steelers won 4 superbowls in 6 years in the 1970's. I don't think the simpleness of saying "6 in a row is still more" is reasonable.
Fact is that every league, in every sport, deal with dynasties. It is part of sports. The entire makeup of a sport doesn't need to be changed simply because a dynasty is currently at the top.
Take a look at the dynasties here:
http://www.nbcsports.com/greatest-dynasties-sports-history
College
http://www.courant.com/sports/uconn-huskies/hc-ss-dynasties-college-1112-story.html
They haven't completely re-written the sport in those instances either.
In the early 60's Pete Rozelle got the league and particularly the all powerful New York Giants to agree to revenue sharing so that there would be parity. Vince Lombardi chafed against the addition of new teams to the draft pool, particularly those in the AFL (because he didn't really want parity). The inclusion of the AFL and the subsequent drafts insured more parity for Rozelle. Then, years later, the salary cap insured parity. The NFL has definitely changed drastically to insure parity. It is partially why the NFL is the most popular sport in the U.S. right now.
Major league baseball has seen ebbs and flows in parity. They use a wide talent pool built from a specifically crafted farm system that helps with parity. They also instituted revenue sharing, but wealthy owners found ways to get around it and MLB didn't require the same accountability as the NFL. So they are seen by some to have been less successful guaranteeing parity. Others use playoff statistics from year to year to insist that Baseball actually has more parity than the NFL, but I'm not sure I agree with their conclusions.
In any event both sports have at least taken strong actions to try to insure some form of parity in the league. Like Rozelle saw, they gain a bigger brand for the sport by increasing viewership in many markets rather than just NY.
I think the Bundesliga would do well to look into how they can increase the brands of most of the teams in the Bundesliga. I just don't know how they should do it. For instance, you remember when we were in Berlin? There was Bayern memorabilia all over the place for sale. Andreas even scoffed at it. Yet did we see Hamburg stuff, or even Schalke, or Leverkusen or others? Not that I saw. Granted, we only went into the KaDeWe that one day. But in the street markets in Berlin/Brandenburg, Bayern stuff reigned supreme.