PlumShots from the Dpreview forum writes:
E-M1.2 F/W code is being optimized/refined much of which will be incorporated into E-M5.3 F/W.
New/upgraded features/algorithms/codecs are currently being tested as part of the E-M5.3 alpha/beta cycle and most will be made available to the E-M1.2 once finalized.
If his “rumor” is correct we can expect some of the E-M1II firmware update features to be included in the future E-M5III. The E-M5III is likely to be introduced at Photokina in September 2018.