I'd rather dream for an asic miner with very low power consumption like GPU before thinking of any that I can really use in a motherboard, the problem with asic is power consumption, there isn't any graphic card yet taking 1500watt to 2600watt....
1500w-2600w asic via usb riser(gpu riser) is very doable, the problem is the "standard" of PC, it means there is a OS, CPU, hdd/sdd, rams, PSU.
i mean, the asic manufacturer would sell a 3500w desktop psu along with an asic? a 2000w unit cannot be 6 inches beside another 2000w unit, usb riser will be 1-2 meters to be ideal with the PC motherboard at the center. (4pcs ASICs.. up, down, left and right that's the best setup LOL)
or
the asic manufacturer sells an asic with a psu, that says in the manual, "only to power the gpu riser and the asic itself"?
there are many points of failure with this kind of market, a lot will be RMA'd or rejected RMA due to wrong pcie insertion, PSU power cabling, and cooling negligence for users (asics already designed the air flow)
analogy: same thing with routers, you could use a PC and install an OS for internet routing (with all the disadvantages of PC hardware) or just buy a compact, low power, low failure rate, small size routers.
we long time miners can really do it if it is sold to us, but imagine the newbs and FOMO miner idiots that would flow to the mining space due to bullruns hehe, these idiots account to majority of miners during bullruns, imagine that they can impact gpu prices during bear market LOL