No you shouldn't hold your breath for an update.
Apple has the muxing unit between both the gpus and they simply don't provide drivers under Windows for it. To Windows there is only the dGPU ever exposed and looped through the muxing unit by default apparently. The firmware simply doesn't let Windows in on the iGPU. It is not a missing feature, it is a deliberate choice. They would just have to make both available and provide or at least allow installation of the standard Optimus driver to allow swichting. Optimus is entirely in software and really only needs to get access to both GPUs. It cannot work without access to the Intel GPU.
Apple won't ever change that because they could have, ever since the 2010 models without much effort. They don't probably because they want OSX to look better besides Windows in battery life and heat characteristic. My guess or they are just incredibly lazy with bootcamp.