Only a sell-out crowd in 2016 will secure the future of the German Grand Prix at the Hockenheimring, as bosses warn its return next season isn't indicative of any firm assurances beyond that.

For the first time since 1960, Germany will not host a round of the Formula 1 World Championship this year after Nurburgring first withdrew its interest due to financial issues and no deal could be reached with the Hockenheimring to step in.

Though the official word for the event's cancellation was justified by the short lead-in time to promote the event, the German Grand Prix has come under scrutiny in recent years for dwindling spectators figures. This is despite Sebastian Vettel's four world titles between 2010 and 2013, while only 50,000 turned out to see Nico Rosberg and Mercedes clinch last year's race win.

As it stands, Germany and the Hockenheimring will be back on the 21-strong calendar for 2016 in honour of its original rotating hosting contract with the Nurburgring, with the provisional schedule returning it to its traditional late July slot.

However, on the week this year's race was supposed to be held, organisers say it will still take a big increase in the 2016 audience to assure its place on the schedule going forward.

"We need a full house next year so that Formula 1 has a future," Hockenheim's managing director Georg Seiler, told German press agency dpa. "We must tell the fans: come to the race next year and secure the future of F1 at Hockenheim."