Ich würde und werde mir wegen 4k alleine sicher keinen Nachfolger kaufen und ich kauf mir deswegn auch kein GX8 oder GH4, aber in einem FW update für meine eigene E-M1 hätte ich 4k trotzdem gerne. (und focus bracketing)
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1) Focus Stacking Mode (OM-D E-M1 only)
Focus Stacking Mode let you shoot macro photos that are completely in focus at all depths. A single press of the shutter button captures 8 shots with different focal positions, automatically merging them into a single shot on the camera. Depth of field larger than that of minimum aperture and high resolution without diffraction can be achieved.
Also kein normales 4k Video, aber das was Olympus da bietet ist trotzdem SEHR cool!
Hier mal die Liste der Neuerung für die E-M1. Auch den silent Modus nehme ich sehr gerne mit.
Focus Stacking Mode
Focus Bracketing Mode*2
Advanced Focus Peaking (4 colors)
Silent Mode (electronic shutter)
Improved Anti-Shock Mode
Support for Advanced Olympus Capture Ver. 1.1
S-OVF (Simulated OVF)
4K Time Lapse Movie
Support for Live Composite on OI. Share
MF Clutch and Snapshot Focus Disable*7
Menu Cursor Position Memory
Movie image stabilization with 5-axis IS and digital IS (M-IS1 and M-IS2 supported)
Support for 24p (23.98p)/25p Frame Rate
Movie Info Display
Movie Rec Start with Release Cable (RM-UC1)
Support for Time Code Setting
Generate Slate Tone*8
Synchronized linear PCM Audio Rec*8 with Movie Rec*8
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*1 The following 3 lenses are compatible: M.Zuiko Digital ED 60mm f2.8 Macro, M.Zuiko Digital ED 12-40mm f2.8 PRO, and M.Zuiko Digital ED 40-150mm f2.8 PRO. Approx. 7%of the top and bottom, left and right are cut out from the composited image.
*2 Micro Four Thirds standard AF lenses are compatible.
*3 Focus Peaking is not available while recording movies.
*4 Supported shutter speeds are 1/8 to 1/16000 sec, and supported ISO speeds are ISO LOW to 3200.
*5 Adds sequential shooting in Anti-Shock mode when the time from a full press to the beginning of exposure is set to 0 sec. and first-curtain electronic shutter will be used all delay times.
*6 Except for High Res. Shot.
*7 Applicable lens firmware update required for MF Clutch mechanism and Snapshot Focus mechanism.
*8 Supported with Olympus Linear PCM Recorder LS-100
Quelle:
http://www.olympus-global.com/en/news/2015b/nr150915omde.jsp
Gerade per Zufall auf oly-e.de gestolpert und geglaubt ich träume 
. Ob es zur Überbrückung bis zum Erscheinen des E-M1 Nachfolgers reicht, wird sich an den Verkaufszahlen der E-M1 zeigen...
