This car's "limited production" is really not that limited - at least not compared with several of these types of similar editions of the line (original GT 333 each of Coupes and Spyders worldwide - the same; 2010 LeMans editions 30 cars, all Coupes, 15 V10 and 15 V8; 2014 LMX cars 99 units worldwide - none here; 2015 Competitions - some similar bits as the GT for 60 units for the US; 2017 another LeMans 24 hr - 15 units for the world - none here; 2017 Micromata Spyders - 4 units for the US; 2017 Quantum Edition 25 units for the US; 2017 Audi Sport Special edition - 1 for the US - AFAIK; 2018 Competition Editions - 10 for the US; 2019 Audi Sport Performance Parts edition - IIRC, 10 units for the US; 2020 Deceniums - 50 for the US; 2021 Panther Editions 20 for the US...)
Anyway, most of these have pretty obscure "collector value" now, so it's really hard to say how even the last GT will do. The Heritage TT RS was more special for those 50 units, at least in combinations, but values aren't much better now than the rest of the other 60 or so cars for the same model year... If the R8 GT was as special an edition as the first, I would be inclined to think otherwise - I suppose time will really tell -