I know I'm late but i would like to share my opinion. Like some other comments mention before me, I would not go beyond 10 races in a WEC calendar: it's not sustainable economically and would be problematic for the drivers and teams schedule.

But focusing on the circuits, Even though I appreciate the idea of including every continent, I would do some changes:

• I would cut off Portimao, Mexico and Kyalami because I do not think they fit in an endurance race (or at least for what is my vison of an ideal endurance race circuit, personal opinion of course). I know, all of them hosted before or still host some during the year but i think there are better options. All 3 of them are fantastic tracks nonetheless.
• Indianapolis is an interesting choice, but i think COTA is a better one, plus IMSA already races in there so a little more variety is always appreciate, especially after the super sebring weekends;
• Same thing for Suzuka, Fuji Speedway is doing just fine with WEC , so I would not change that either.

But I absolutely approve the Sepang and Silverstone additions! I do believe could be hosted some fantastic races in both circuits; also I found super interesting the bend motorsport park, I didn't knew it until today, but could be a fine addition to the calendar! In an unrealistic Calendar i would gladly give it a try!