Matthias Schrader/Associated Press
Perhaps the most important and iconic event in German football this summer, unless Germany wins the coming World Cup in Brazil, will undoubtedly be Lewandowski's transfer from Dortmund to Bayern.
Like Goetze before him, the Polish striker has chosen to move on from Klopp's side in the pursuit of even higher glory at the current German champions. The move will do little to reassure Dortmund fans of the future success of this side, yet it's one that could completely reshape and reinvigorate the team.
Top-quality strikers such as Adrian Ramos have been linked with summer moves to the old mining club to replace the departing forward, as reported by Stefan Uersfeld of ESPN FC, yet nothing concrete has been confirmed.
However, even if Klopp opts not to sign another top forward to replace Lewandowski, he does have talent among his squad that will be just itching to try on that No. 9 shirt.
Pierre-Emerick Aubameyang is the most obvious candidate for the job, having already scored 16 goals from the right wing in his first Bundesliga season, according to transfermarkt.co.uk, despite actually being a natural striker. If Klopp wants a goalscorer next season then there are few better in Europe right now than this young player.
Alternatively he could turn to Henrikh Mkhitaryan. The Armenian forward signed last summer for a substantial fee doesn't quite score as many goals as Aubameyang but distinctly approaches the game in a similar fashion to Lewandowski. Again, if Klopp is looking for a forward who could so readily move into the Polish forward's role then he already has one at the club.
Away from the more direct route of replacing the departing striker, Klopp will also have Jakub Blaszczykowski back from injury next season, while the likes of Marco Reus and Jonas Hofmann will continue to only get better and better, admittedly at different stages, throughout the summer.
Dortmund may be losing its best striker, but the forward line couldn't look better for next season.