Dortmund resurgence down to Klopp though and about to lose Lewandowski. It won't be long before Klopp moves on either to Real Madrid or DFB, also elite teams are going to continue to cherrypick their best players. Dortmund is not a glamorous part of the world at all, so will always struggle to attract top overseas players and keep their best one. Financially their ticket prices are rock bottom (and fans won't allow a big increase).
Edit: As stated, the league will progress. The fact Dortmund have progressed to be a squad in with a shout of winning the CL (whilst still 15 point behind Bayern in the League) whilst we're now nothing but cannon fodder for the best teams, plus Chelsea' Channel 5 romp and City's early exist, is a possible indication of where things are going.
City's early exit is due to Mancini's incompetence in Europe, was the same for him at Inter. With a proper manager they would perform well with current squad.
Chelsea/Arsenal, one of these likely to be replaced by a much more competent looking Spurs. Which will likely be a good thing for either of them in forcing an improvement in how they are run.