Great post as always Andrew, but my concern is what we might LOSE if the GH5 goes with a larger sensor. What Panasonic has done so well with the GH line is exploiting all the benefits of a smaller sensor. For instance, if a m43 sensor means giving us 240fps at 1080p as opposed to 120fps on a s35 sensor, I would go with the m43 sensor every time. Hell, maybe we could even get a global shutter this time around? At any rate, there are certainly many benefits of a smaller sensor that can potentially outshine the step up to s35. I still think Panasonic should continue separating this format by offering kick ass specs that larger sensors can't offer. That might even mean having to do a complete technology overhaul for m43, which it sounds like they are already working on. See below.
http://blog.planet5d.com/2016/02/a-sensor-that-can-shoot-in-starlight-panasonics-apd-cmos-could-change-low-light-forever/