The German, Canadian and Brazilian grands prix were listed as subject to confirmation on a record-equalling 21-race provisional calendar for 2017 published by Formula One's governing body on Wednesday.
The Italian Grand Prix at Monza, whose place had been doubtful up until this month's race when a deal was agreed if not signed, was listed in its usual September slot after Belgium.
Germany remains uncertain due to Hockenheim's stated reluctance to host a grand prix other than in alternate years and no deal with the Nuerburgring. The country's race was dropped in 2015.
Formula One's 85-year-old commercial supremo Bernie Ecclestone has also been pushing for improvements to Montreal's Circuit Gilles Villeneuve, whose contract is up for renewal next year, and the Interlagos track in Sao Paulo.
Brazil is also suffering its deepest economic recession in decades but local race organisers were taken aback by the development.
"The Brazilian Grand Prix Organisation took notice, with surprise, of the 2017 F1 WC Calendar which shows the race TBC (to be confirmed)," they said in a statement.
"There is a contract in place until 2020, every provision of which will be complied with as it has been for the past 45 years."
Ecclestone had warned in June that the 2017 calendar could be reduced to 18 races, although Monza was seen as one of those on the hit list at the time.
With no races added, after the debut of Azerbaijan's Baku City Circuit this year, the main changes were date shifts and the reshuffling of some pairings.
There will be seven back-to-back pairings, and four in a row during the European part of the season.
Canada and Azerbaijan in June are on consecutive weekends, with the latter again clashing with the Le Mans 24 Hours sportscar race, as are Austria and Britain in July, Hungary and Germany at the end of that month and then Belgium and Italy.
Malaysia will precede Singapore, a reversal of this year, and stands alone on Sept. 17 with the neighbouring night race on Oct 1.
Singapore and Japan are back-to-back in October while Mexico's race, which is paired with Texas this year, was moved closer to Brazil with those two on Nov. 5 and 12 respectively.
China's grand prix in Shanghai, the third round this year, reverts to being the second, on April 9, and is back-to-back with Bahrain on April 16.
Australia hosts the opener in Melbourne on March 26, a week later than the 2016 season's March 20 race. The finale will again be at Abu Dhabi's Yas Marina on November 26.
Image: Nico Rosberg of Germany driving the Mercedes past a marshal on track during the Formula One Grand Prix
Photograph: Lars Baron/Getty Images