7K HPS would be 3.5K TPS, which means a tank only needs to generate 2.7K to keep aggro off you assuming you are staying at range. If your tank can't manage at least 2.7K TPS, they need to work on their rotation. Outside of a couple of very specific situations, healer threat drops should be completely unnecessary at end game.
That might be true if you're in a somewhat skilled guild but I've reched the point, both as DD and healer, where I'm actually surprised if the tank manages to keep aggro throughout a pug raid. And I'm not just refering to specific scenarios lthat are commonly known as tricky for the tank, like Kephess on TfB (aggro is always all over the place on that one).