This being the case, conventional wisdom for shooting concerts, etc, I think would still push you to prime lenses. Say a 35 f/1.4, and 135 f/2. But one of the things I am watching is just how much of a game changer is the high ISO performance of the 6D/5DIII/1DX. By game changer, I basically mean that the importance of getting light through the lens may become less significant. What I am finding is that I can take shots up to ISO 12,800 on the 5DIII and be very happy with them. The non-visible quality isn't as good as I am noticing that the higher I go with the ISO, the less ability I have to crop and/or post process the photo before I start to see too much IQ degradation. But for visible IQ, if I nail the shot in camera, ISO 6400-12,800 has good IQ.
An illustration of this is that a few people that previously have said that f/2.8 isn't enough for low-light indoor photography are starting to say that with the new bodies, f/2.8 is enough. I am still getting used to the abilities of the 5DIII, but thus far, I've yet to put my flash on the 5DIII and have shot two indoor "events" (meeting my new neice and Easter) with the 50 f/1.4 at ~f/2.8.
Aperture will always have the advantage for those situations where you want thin DoF, but it may becoming less important for light gathering. Just something I am watching in my photography and in what I see posted.