Cinima5D has a great very video centric interview with Fujifilm Manager Takeshi Ueno about the Fujifilm GFX 50S. Fujifilm thinks that over 80% of their customers are satisfied, but professional and amateur landscape artists have requested a higher resolution system, which lead to the development of the GFX for such customers. 4k definitely wont be available, but full HD will, so the only real video advantage the GFX will have is the unique look of medium format, because right now all medium format sensors are designed for photos. The GFX should be used for shooting photos 80-90% of the time. The sensor read out speed isn’t fast enough for 4k, but the processor could do 4k so maybe the sensors will catch up in the future. Fujifilm will mainly design high quality primes for this system that far exceed APS-C/Fullframe lenses. There is also some talk of 8k at the end and if large sensors might be the way to go for the format and how in the future 100MP could lead to some interesting lens designs. For now the most important thing is to price the GFX to sell well so more people can use the format.