I just cringe seeing this topic come up again - but as usual it has digressed into multiple topics.
I don't see m4/3,DX,FX,MF or almost any sensor size dying. I do see more invented just as the J1/V1 series. Just as there are different camera mounts, there will be different formats. What will kill the formats are not how good the quality they produce is, but languishing sales. DX & FX are standards and will not go anywhere soon. M4/3rds - I think Olympus's troubles and if the camera division survives, will be an indicator but it won't go anywhere soon.
Many tech ideas have died - remember Canon's follow the iris of your eye - auto focusing? Now that was great, but the older AF tech advanced enough that it was replaced. Will the flapping mirror go away? Canon's new 14fps utilizes the mirror lock up to achieve that FPS. Will the focus be on? Will the split second blackout hamper anything? We will wait to see. Many forget the mirror is an integral part in the auto focus systems. Sony modified it for video. (Maybe I'm the only one who doesn't see it as a revelation - translucent mirrors have been around for hundreds of years. It was only a matter of time.) The fact today is, AF of mirror-less cameras don't even come close and success rate are aided by larger depth of field of smaller sensors that have more leeway for error. Put that tech into a FX with a 1.2 DOF... Will our eyes want to look at a mini lcd-type screen over the clear viewfinder? In low light with my x100, I love it except that I can't see anything when I look away until my iris resets. In daylight, no, I still like the "real view".
We will all hit a point of what format, AF type, etc. that is best enough for EACH of our photography styles, needs and yes, price. At least for now and the next few cycles, I see more flowing to FX then flowing backwards to DX or smaller. At the same time I do see more people becoming "comfortable" with DX and smaller and feeling less of a need for FX. Is that statement earth shaking - not unless you are an ant on a marble.