What is stopping a company like Shuttle or ABS build us a CableCard barebones

The key to cablecard is the requirement of Windows Vista Ultimate and a motherboard that supports Cablecard right? So why can’t they give us the OS, motherboard and the cable card tuners and leave the CPU, memory and hard drive configuration up to us?

From the appearance of the lifeware box it looks like the cards sit right in PCI or PCI-X slots and extend out the back of the case for inserting the cable cards.