An "updated D300s" style body (a.k.a. D800 with a DX viewfinder), Multi-CAM 3500DX, D7000 sensor, 10fps, $1800 I'd be all over that, although the 24MP sensor from the D3200 would be a nicer upgrade incentive. The size of the data pipeline becomes the gating factor here. The D4 proves Nikon's pipeline can do 10fps @ 16MP. Extrapolating from D4 & D800 data rates, it seems 24MP would be limited to 6-7fps with equiv-tech. Either I would consider an attractive option. Given a preference I'd probably ask for 24MP 7fps.
How big is the market? I have no idea, but the niche is distant, fast-moving wildlife with a small enough lens for the photographer to remain mobile. This is the only place where D300s is still king.
Given Nikon's apparent prioritization of the AF-S 80-400mm f/4-5.6 VRII, which would also nicely fit this niche, you're probably correct Stan, that Nikon doesn't see this as a lucrative market.