I also doubt that the power consumption of such an extra chip would make it worth it.
Lucid Hyrda is really only worth it if you drive some high end gaming rig, in any other case simply buying a faster GPU or notebook serves one better.
Also it never really took of because the market for it is way to small. SLI and CF got better driver support and don't require any extra stuff. The micro stalls, lag and all those AFR problems exist but the majority doesn't care because they only use one GPU anyway and upgrade. For the small enthusiast group AFR is and I suppose will be the only viable option because it is simple.
The Hydra chip is old and the 2nd gen was out but ever only used on one or two ultra high end mainboards. I am not sure if it still exists. There is just not enough money in the market to make it worth it and really work out the kinks.
With an HD 4000 and the poor driver performance it would net 20% more speed in the best of cases and zero or less than that in many others. You get in exchange artifacts, other errors, instability. Would never be worth it. In IT all things are a trade off between programmability and speed. Even if speed is great but if it is too hard to use and make work it is not viable.
BTW. I also think that some special post processing could be done simply by changing the Optimus, ADS drivers. Without any extra chip necessary. The output framebuffer is written back to the HD 4000 anyway. Yet usually it just puts it out to the screen and the EUs and everything do nothing.
With some extra driver tuning one could force the HD 4000 to run post processing effects like morphological AA or artifact reduction and similar stuff that is not geometry dependent. Still the use would probably be limited as only MLAA to my knowledge would really be of any use here. MSAA is not that expensive and still better in most cases than MLAA so why would one even bother for offloading one feature that most people would probably end up not using.