I gotta side with the Pupil here. We know exactly what he will do. He runs in them now and has since early '16. He has never run a marathon without them. He can get a number in any race in the world. He has run exactly the races he (or Al) wanted to.
What can he do in perfect weather, perfect course half? The closest thing to a BTC-type time trial? And wearing the exact perfect shoe? He did exactly this, and didn't get anywhere near sub-58, sub-59, nor Hall's AR (which, incidentally, was run in a real race, without any pacers brought by him or otherwise, and without 'The Shoes').
What about a flat, fast, marathon. In good weather, and with the latest shoe technology? He's done this too. Chicago set one up for him. Everything perfect.
A couple minutes slower than Hall on the same course was the result. (Did I mention the shoe dissimilarity compared to Hall's?) Ran another in Europe. Got a few seconds on Hall this time. That's what Rupp can do with the latest $200-300 shoes. We saw what happened when Chicago didn't clear the field for him. Had guys to run with the whole way. Paid pacers most of that, then competitors to chase until the end. He did get dragged to within a couple minutes of the AR! Even got into the top-10 in the race!
Covid or not, he most certainly HAS had the opportunity to run. The Trials let him run. Another 10 seconds per mile and he'd have been close to what Hall ran on a hilly course. (Rupp tried that course too, had company and guys to chase the whole time, not to mention The Shoes, and almost got within 5 minutes of Hall's time!)
Viruses notwithstanding, he put together the much-hyped AR record attempt on the bike path. Cool, pool-table flat, personal pacer. This happened during the whole Covid crisis, did it not? Did he wear old Streaks for this? If so, maybe we don't know what he could do with the latest, most expensive shoe on the market (or maybe not yet). Oh, he DID wear them. Oh, OK.
This debate may be relevant for someone like Kannouchi. Another thread speculates on exactly that. What someone who had access to the technology in question since it has existed (even before it could be purchased) - in his prime - is not worth speculation. This experiment has been held in real life.
The result? No World Records. (Nothing close.) No American Records (all he has predate The Shoes). Within several seconds of Ryan Hall in both the half and full marathons. Dodged London, Berlin, Dubai, and every fast Japanese race. RAK and every race in Valencia went on without him, even though he had similar shoes to everyone else. We know to the second what he's capable of. Now that this has been pointed out - and yes, The Shoes existed during his prime years - there is no need to guess, wonder, or grant him records and wins he didn't actually achieve.