The reason for the existence of this product, if it does indeed exist, is actually in response to the RRoD. On all 360 systems, new or old, the possibility of the RRoD exists (though it is lessened in newer models). This is because Microsoft rushed the design, choosing its cabinet style over performance in a bid to beat Sony to the consumer market and look cool doing so.
The problem is actually the motherboard and the placement of its components: it doesn't allow for proper cooling and in point of fact does the opposite. Over time the board warps from excess heat, the glue holding the GPU severs and melts, and chip becomes detached from its designated location. They've come up with fixes to help prevent this, but they're bandaids at best.
To make a somewhat technical explanation shorter, designing a whole new motherboard is the only true method of solving the RRoD. The components need to be placed differently and designed in a way that allows for optimal cooling. If they can accomplish that, which is really the only reason for designing an slim 360, they'll be golden.