https://twitter.com/WarcraftDevs/status/656577173902372864
There's no hard weekly cap this time around, but at some point you will run out of Valor-awarding activities.
If you are a raider you will be doing Heroic dungeons daily, the weekly quests for Valor,
all of the LFR wings weekly, and the Mythic dungeons weekly.
Is this what you wanted? Will your guild expect you to do all of this? Do you like this? I play a lot, but I dread even thinking about doing all of this.
IMO, we do have a cap. It's a bit over 4000 Valor. To reach that one would have to do LFR weekly for it. I'd rather LFR be taken out of the equation entirely as I would not have issues running semi-challenging content in Dungeons at the cost of so much Valor income per week. The fact that running LFR determines if we get either 7 or 9 upgrades per week potentially on our gear is what a lot of raiders have problems with. If you made it so you could run
either LFR or heroic dungeons, but not both, for the same amount of valor that might be a happy middle-ground as they're both trivial content.