I think you're putting the cart before the horse.

Pretty much any computer can host a USB FPGA or ASIC miner, even a rooted Android device with an OTG cable and BFL's Android mining software.

The trouble is that as more and more ASICs are shipped and as difficulty skyrockets, FPGAs are rapidly becoming obsolete.

That leaves ASICs as the only practical solution and waiting lists are so long as to make them a questionable investment at today's prices if you have to wait until difficulty is in the hundreds of millions to get delivery.