Overcoming the obstacles
Some of the practical issues with the GH4 are design limitations, some relate to the format, and some to what are, presumably, commercial decisions by Panasonic.
A hybrid camera will never offer all the features of either a dedicated stills-focused DSLR or an ENG video camera. Stills in particular, will always benefit from full-frame sensors that work well in low light. The GH4 has to pack more into a smaller sensor, and Panasonic has done a commendable job, for example, in increasing the frames per second on stills. It has the potential to be a great time-lapse camera too.
The lack of ND filters is something that faces all DSLR users; it is possibly less of a drawback on Micro Four Thirds than it is on full frame. An ND filter is only a small addition to a kit bag.
The issue of lens support may take longer to address.
The lack of ND filters is something that faces all DSLR users
The Micro Four Thirds system is easy to adapt to use other lenses, and lens adapters are so popular, especially in the video community, that this may be holding back lens development. But support for the Micro Four Thirds system is growing, and this should boost lens options.
The new Blackmagic Design studio cameras use M43 mounts. So too will the upcoming JVC 4K camcorders; JVC has joined the Micro Four Thirds group, and will use the mount even though its 4KL cameras will have slightly larger, Super35mm sensors.
More third-party lens support, though, would boost the GH4’s prospects. It would, for example, be great to see a M43 native version of the Sigma Art 16-35mm f1.8: a version of this bright zoom would be a great companion for the GH4. Sigma has already done commendably well with its low-cost, f2.8 M43 primes.
The GH4 will, too, need to overcome some teething problems, such as a reported issue with audio via external mics. Some early video tests suggest that the 1080p video modes could be cleaner too (these don’t use direct sensor read-outs but instead, employ pixel binning). Hopefully, these are issues that can be addressed via firmware updates.