Not only does Canon need a new sensor to really steal the market; they need it give the 7DMII something other than a mostly software update over its predecessor. Otherwise the only area of improvement will be the AF and the 7D already has AF better than most need.
IF it had only been a year or two since the 7D that would be fine, but its been a long while now, the 7DMII is almost sitting in a spot that a 7DMIII would be sitting in so its got to be show-stealing to really get existing owners to really push for an upgrade early; and nothing will do that more than a new sensor.
Similarly a lack of a new sensor will be a bad marketing move overall; esp since the 7D line is now the highest tier crop sensor they produce (no 1.3 1D line crop any more). It would almost be better to not release the new camera than to release it with the same current gen sensor (unless they do some utterly fantastic software that revolutionises it).
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