The challenge to the manufacturers remains the production of a large sensor (3K), less than $6K body, properly-featured camera that shoots RAW stills and video with equal success. RED is there at $$$...so
There's the question of frame rates - How hot does a sensor get at 120fps? Also, imagine RAW conversion for thousands of clips on a huge project! I think uncompressed 4:4:4 is good enough for the purposes video/cinema was invented for. But who knows about the future? For resolution's sake, the Epic is right alongside IMAX.
In the digital realm, 2K enough - for two reasons:
1. The average cinema resolution is 1.3K or less, except for the ones with 4K digital projection, which might be around 2.5 to 3K in reality.
2. The standard maximum consumer TV resolution is 1080. Gaming and grading monitors have a slightly larger resolution, but it's still around 2K.
3K really falls in no man's land. There are no display standards for 3K - you either downscale to 2K/HD or upscale to 4K. The question is really not one of resolution but of time and money. If I had enough time and money, why wouldn't I opt for 4K (or even 6K)? The choice is made by how much I have in my wallet.
BTW Sony seems to have solved the jello-cam effect on their latest still/video cameras: one small step at a time...
The F3 and the FS100 have very poor jello-cam (rolling shutter) results - almost on par with HDSLRs. The Alexa is slighty better. The Red MX is worse than the Alexa. The only camera that stands up to film (and high-speed cameras) is the F35, and that's top of the line. (Reference: The Zacuto Tests, part 3).
One must remember the RED has a crappy form factor too, and needs a rig similar to an HDSLR rig.
The key is to know which system to use in any given situation. I can't fault the manufacturers for giving me so many choices in possibly every price bracket (The iPhone 4S supposedly has great HD video). To be really fair to Canon, they initially never marketed their cameras as filmmaking tools. I must blame myself for using my tools clumsily.