I think 15w/th is doable given that S19xp is reported to do 18-19w/th underclocked with the proper firmware, so 15-16w/th stock for S21 pro won't be too far stretched.
Keep in mind that while Nick Hansen is the CEO of Luxor and probably has some Bitmain insiders, his info may be totally wrong.
Nick Hansen also let that company's pool push meme spam inside the Bitcoin blockchain cheaper than normal transactions...
And yet the S19 series started with a 7nm part (BM1398) and then moved to a more efficient 5nm part (BM1362) that originally was the J, confusingly now all seems to use this chip regardless of them using the J letter or not; except the XP with the 5nm (BM1366). In the process they degraded the quality with the cheaper aluminum treatment, or from their point of view, "optimized their process" since the fact people were running the miners more efficiently meant that they were leaving "too much" margin for "improvement" (could be made cheaper).
Unsurprisingly, in typical Bitmain fashion, the "newer" models are using the lower yield chips. The "good stuff" left with the 104T and 100T Js, the "non Js" rated for 90/86/82 are simply the lower yield leftovers. Again, typical Bitmain fashion. Too bad some people don't see it and get lured by the "cheap price".
I agree with philipma1957 predictions. Unless they use the recently announced 2nm node by TSMC, but even if that's in the plan, its probably still a year or two away, so like they did with the S19, may actually start with a 5nm part not terribly more efficient than the XP, just like the original S19 Pro 110T.
Desiwe has a more interesting approach, but its just bruteforcing higher efficiency by running parts slower and better cooled (8nm Samsung). But if they manage to upgrade those chips with an even lower node, then Bitmain will have something else to worry. Who else uses Samsung? Ah yes, MicroBT...
