If they don't improve low ISO performance by a stop, what would be the point of upgrading from the D7000 (assuming the new camera has the same control layout and AF module)? The D7000 is already about as good as anybody needs in good light. The extra MP for cropping aren't as big a deal at lower ISO's.
And,...anything less than 6FPS would be a step backward for serious DX shooters - another deal-breaker.
What I want: 24MP, 6FPS min, 51 point pro AF system, and one stop better low ISO, in a D7000 ergonomics body. I'd buy this camera for $1,200-1,500 immediately. If a full-blown D400 came out (all of the above but in a D300 body), I'd wait a year until the price dropped and be willing to buy it for $1,500-1,800 max.
What I think we'll get: 24MP, 6 FPS, 39 point AF from the D600 (not bad, but not a vast improvement over the D7000), 1/2 stop better ISO, in a D7000 body. If that camera sold for under $1,300, I'd buy it. If it was more than that, I'd stay with my D7000 for field sports, and upgrade to an FX D600 for basketball next year.