I used to think the 7DII might come pretty close to FF in IQ and high ISO performance. Until last November, when a thread in CR completely disillusioned me. Next thing, I bought a 5DIII and sold my 7D and I've been kicking myself ever since that I didn't do it a year sooner. So yeah, I totally see what Jrista is talking about [although not cool to use 'trounce' in APS-C vs FF (that too same generation), Jrista, not cool].
I am lucky that I didn't end up waiting for 7DII and be disappointed.
If IQ was my only concern, I could walk into the local bestbuy and grab a 6D for less than what we expect a 7D2 will go for. There is no way short of physics defying magic that the 7D2 will beat it... But for me, I really want a more capable AF system and after playing with the touchscreen interface on a 70D, would like to see the next generation of that too... Hmmmm...... 5D4?
It's clear that a crop sensor can match full frame IQ (I posted the 1DIV comparison for relation to the OP) in some circumstances, not many, but it is possible. We're going to need a lot more pixel density on our full frame cameras to go beyond that.
I think people aren't giving enough credit to the processor when talking about low light. It seems pretty clear to me that the biggest upgrade responsible for that 1 stop advantage in the Nikon D4s is the processor.
Sensorgen doesn't have the specs up for that body so I can't say if there has been a significant improvement in QE or not, but at least Nikon seems to advertise that the processor is a major factor. Of course then we have to decide how much we trust marketing.