gyamsThe rumor mill says there will be an EM-1X coming out early next year. This will not be an EM-1 MK III, but an entirely new camera, with a steep increase in price relative to the EM-1 MK II. Since Olympus typically only releases one or two models a year, I doubt we will see an EM-1 MK III anytime soon.
gyamsOlympus stated a while back that they were shifting to a 4 year update cycle for OM-D cameras. If they hold to that (maybe doubtful given the intense competition) it wouldn't be until 2020.