I have the same decision to make (though coming from an even older 500D)...
I like portraits, and a bit of landscape, but with young kids, sports carnivals, running around at parties, love animals at the zoo,etc.. it just seems other than the top of the line cameras, I have to make a choice and compromise what I want to shoot.
I invested in the 15-85 EF-S which is a great lens, but to go to a 6D I would have to get a 24-105 which is an additional cost as well and from some comparisons I have seen the IQ between then (on the same camera) is quite similar..
I was hanging out for a 7D2, but the more I read it is a real unknown when it will be available and it will also be a top of the line crop with alot of extras I don't need, for a lot more cost. hence thinking I should choose between the 70D and 6D.
If you like your 15-85mm EF-S IS lens (I had one and enjoyed it), then I would go with the 70D. If the improvements to hight ISO materialize, I too might be interested. Like you say, the 7D II will be much more especially if they make it with a built in grip (a la 1Dx). The only thing that worries me about the 70D is the AF performance; I hope it is better than what was on the 7D. There was no mention if there are any double cross type points in the 19 point array. That make a big difference when tracking birds in flight.