Toto Wolff has admitted both Hockenheim and Barcelona will "probably" be missing from the 2020 calendar.
With Vietnam and Zandvoort set to host new races, Liberty Media says it doesn't want to expand the schedule beyond 21 races for now.
It means two current races will go.
Mercedes boss Wolff admits that the future of the German GP at Hockenheim looks "very bleak".
"2019 will probably be the last year. The competition is strong and the promoters do not have the means to fight to keep it," he added.
Wolff, however, backs Liberty in not currently wanting to add to the number of races per year, even though there are rumours the F1 owner wants 25 grands prix in the future.
"I think saturation is something that needs to be considered," he said. "Formula 1 is exclusive and adding more races is not adding to the exclusivity factor."
