Or become a chip company and focus on providing chips for others to use in their product.
In the long run I think the successful ones will. Look at Bitfury. They sell no boards to the public instead they wholesale chips and rely on three major OEM (US, EU, Russia). Think of how well that allows them to focus on the core task of chips, chips, chips. Given their 55nm design has higher efficiency (J/GH and GH/mm2) than some 28nm designs it seems to be working. If I was a ASIC company I would be worried about what a 28nm die shrink will look like.
Even AMD doesn't make graphics cards. They make GPUs for a dozen or so OEMs which make graphics cards.