Struggling Hertha Berlin face an uncertain future despite a decision to allow postponed repayment of a high-interest loan, which effectively ensured a German FA (DFB) operating licence next season.

Relegated at the end of the season after several years treading water, indebted Hertha face an increasingly competitive second tier.

The club negotiated an extension on the 40-million-euro ($43-million) loan, initially due for repayment in 2023, until 2025, clearing the way for the DFB to approve the club's licence on Monday.

Failing to secure a licence would have meant relegation to the fourth tier.

Making matters worse, cross-town rivals Union Berlin qualified for the Champions League on a comparative shoestring after just four seasons in the top division.

That Union look set to take on the European elite at Hertha's 75,000-seat Olympic Stadium highlights the unmet potential.

- 'Only mistakes' -

When millionaire Lars Windhorst bought a 37.5 percent stake in 2019, he promised to take Hertha to the top of German football.

Four years later, Hertha were relegated despite spending an estimated 374 million euros ($412 million) on players.

In May, returning manager and club legend Pal Dardai criticised the costly arrivals for being "satisfied with their life, their car and their chic looks" rather than the club's plight.

In March, Windhorst sold his stake to 777 Partners, who also own Spain's Sevilla, Italian side Genoa and Belgium's Standard Liege.

While the American private investment company have taken over Hertha, and their debts, the multi-club ownership model means the amount of capital available is unclear.

Daniel Trousil, from fan organisation Hertha Freunde Berlin Sud, told AFP he was "composed and prepared" for Hertha's "painful" relegation, which "had been hinted at over the past four years."

The 45-year-old said "since the arrival of Windhorst and the unexpected wealth, only mistakes have been made", calling the millionaire's reign "restless and disturbing".

Another fan, Sven Schloesinger, 52, said: "the club and its management burned all investor capital through haphazard player purchases, building a team which was not ready for the first division and was rightly relegated."

Trousil shares the sentiment, saying "at the end of these serious chains of mistakes, there's relegation".

- No 'second Hamburg' -

Dardai's decision to stay as coach is also a positive. The no-nonsense manager wants to build a future around Hertha's talented juniors.

In the medium term, Hertha's hopes of financial stability rely heavily on a return to the top division.

Twice in the past 25 years Hertha have come up immediately after relegation, but fan Tim Haas fears things are different this time.

"It's not like the last couple of times when you're relegated and then you're the favourite to go up."

The 33-year-old Berliner said the Bundesliga presented "a completely different economic situation" this time.

Heavyweights Schalke and Hamburg are also pushing for promotion in a division which contains several other traditional top-flight clubs such as Nuremberg, Hannover and Kaiserslautern.

The Hamburg example is particularly worrying for Hertha fans.

The former Champions League winners stadium had a clock recording every minute the never-relegated club had been in the top division.

In 2018, Hamburg did go down and, despite a budget higher than many top-flight sides, have spent five seasons in the second tier, twice losing the relegation playoff against a first division side -- once to Hertha.

Trousil said he "doesn't expect direct promotion" this season and "hopes that we don't become a second Hamburg."

The other club on Hertha fans' minds is Union Berlin.

Schloesinger said he has "huge respect and recognition" for what underdogs Union have achieved, saying "as a Berliner I find it good that Berlin has a team in the Champions League".

Haas disagrees. "Personally I find it quite horrendous. It's disgusting!"