The postponement of the Chinese Grand Prix, which few doubt will eventually morph into a full cancellation, is an unusual event in the modern era. In recent years, the Formula 1 calendar has been pretty solid, even though the first official version is usually published as early as June or July of the previous year, to coincide with the summer gathering of the FIA World Motor Sport Council.
The odd date may change or be shuffled around, but losing a complete race, especially after the definitive calendar has been ratified by the WMSC in December, is a rare occurrence.
Cancellations were more common in previous decades, when there was was a more relaxed attitude to finalising the calendar. Races often disappeared, mainly due to either commercial or safety reasons.