The FIA World Endurance Championship is poised to feature a reduced schedule in 2018, with the elimination of up to three rounds, a possible post-Le Mans start to the season and evolution to a winter championship.

Increasing questions, meanwhile, surround the future of its traditional season-opener at Silverstone.

Multiple sources have indicated to Sportscar365 that the famed British circuit, which has been on the calendar since the championship’s formation in 2012, is unlikely to return.

Silverstone is believed to be one of a potential three races on the chopping block, which could reduce the season to a six-round championship amid the recent LMP1 fallout.

Events at Circuit of The Americas and Mexico City are understood to be among those also in question, with contracts at both circuits expiring this year.

As a result, a more drastic change to a winter season, which had been under consideration in recent years, could be made, with French media reporting the 2018 season may not begin until after next year’s 24 Hours of Le Mans.

WEC CEO Gerard Neveu revealed in May that changes to the calendar and race formats were under consideration, including a possible reduction to eight rounds at that time, as well as the addition of qualifying races for GTE-Pro cars.

While plans for qualifying races for the top production-based class, which welcomes BMW next year, appear to still be on track, the likely changes to the overall calendar are believed to have been prompted by the developing LMP1 situation.

Toyota, the lone remaining factory squad in LMP1, could take part in a limited season next year, which would leave multiple events without a manufacturer entry in the top class.

It’s understood at least six rounds, on three continents, are required for the WEC to retain World Championship status, which it intends to do so thanks to the new-for-2017 world titles for GTE manufacturers and drivers.

The series launched in 2012 with an eight-round season before adding a ninth event, in Mexico, last year.

Both Neveu and ACO President Pierre Fillion have been unavailable for comment since Porsche’s announcement last month, although a press conference has been scheduled for Friday in Mexico City, which could reveal further details on the championship’s future.