You have made a good point about the 5DIII birthday. I was surprised when Canon came up with the 7D2 without a significant sensor jump. However with Lexar making their 2000X SD cards UH3, perhaps in the next year (or 2), Canon may feel that it is time to have a high MP sensor with dual processors to give a 6FPS rate.
Highly doubt you'll see much more than 4 FPS from any cameras wielding the next gen of high MP sensors in the near future. The Sony rumor is a 46 MP sensor is coming, and their folks aren't expecting a high frame rate at first either.
I think the cadence would be:
2015 -- High MP FF rig with modest frame rate, say 4 FPS
2016 -- Same sensor with a souped up processor / buffer / card throughput and (what) 6-8 fps?
The missing bit for me is what Canon will do with another FF rig due for an upgrade -- the 1DX. It was supposed to be the merging of the studio 1Ds line and the sports/wildlife 1D4 line, and it was decent at that task. I say decent in that it's a stellar camera, but each camp had one hand behind it's back -- studio/landscape wanted more resolution and sports wanted APS-H reach.
, a new 50 MP FF rig cannot possibly push out anything near the 12-14 fps the 1DX can now (not at full res at least). So Canon is stuck with a difficult choice here:
- Split the 1DX back into its two camps and offer two new 1D bodies: one that is high res / low FPS for studio or landscape work and another with a different lower-res sensor that maintains a high burst for sports/wildlife
- Only offer a studio/landscape high MP body and tell sports/wildlife guys to keep using their 1DX's (or possibly their 7D2's) until throughput improves down the road
- Pull a 'sort-of-Nikon' and offer one body that is full res for studio/landscape but at the flick of a switch is a some-sort-of-crop high FPS beast. APS-H fanboys can stop spooning with their 1D4's at night and move on with their lives.
All of those decisions have tradeoffs. Not sure which is best.