Wasn't one of the reason's for starting the LMES to rebirth the classic 1000km races. I couldn't see them adding new races at Valencia or Brno for that reason. As has been mentioned Brands Hatch could work, but if they went to Japan it technically wouldn't be the LMES anymore would it
In many ways 4 is probably enough. Add those 4 to Le Mans, plus maybe Sebring and the Petit Le Mans, the proposed 'World Cup', and then a team has 8 or so races already to attend.
I do like the look of this series though. Proper endurance races like the old days, what European SPortscar racing has been crying out for since the end of Group C.