i would not want to wait that long.. but when a new generation is out in 12 month i could wait.There will be no replacements for 5D MK III or the 6D "in 12 months".
By the way, 5D MK III already has an AWESOME sensor.
I would go as far to say the 5D Mark II has an awesome sensor, especially in comparison to what the 7D spits out even at ISO 400 in daylight. But in this day and age with ISO and DR and all the Mark II lags behind even the lower level competition. Of course, in comes the 5DIII, but is the sensor that
better over the Mark II? Well, for ISO, and the brief upgrade in DR and bits yes, while even with the much needed AF, quick response and awesome sealing the price isn't right for what it is today. And considering video hasn't improved much, and some would say degraded with the soft image it produces (although, sharpening is possible, and no more moire at least).
So to the point that I too feel the same way, wait it out for Canon to get back on their feet with real improvements, or get what's available now and use it until that day comes. It's been a year for the MkIII, and if all goes the same then there's 3 more years, that's a whole lot of photos captured in the uber dark, and of the fast action kind. While how's it with the 6D, it's not even a semi-pro camera, and it might get the XXD treatment and have a MKII of that released winter of 2014. Although, if Canon is still Canon today then the "6DMKII" will just have the same sensor anyways