Appreciate your vote of confidence especially from an old guy that has been in our Mustang hobby for the last ~53 years!
Despite what some may say I suggest that I am not biased when it comes to dealing with past, present and future Mustang values based on having owned a Mustang from all 6 generations including purchasing a brand new 1974 Mustang Mach 1 in May of 1973 which as many of us know is the only year that Ford did not provide a V8 engine as an option for Mustang over the last 56 model years.
There is no question that the new and used car market place will settle down with respect to an upcoming price correction and it is just a matter of time for that to take place based purely on supply and demand which includes the micro chip shortage for new automobile production.
Having said that I suggest that our 2nd generation GT350/R's will not follow the same trend of future price reductions and that especially applies to the 2 seat R models of which only ~3,650 examples were assembled over the 6 model years.
Many of you may not be aware of who Johnny Carson was but he was the ultimate "Late Night TV Talk Show Host" and retired in 1992 after 30 years of being the "King of Late Night Comedy".
My opinion which is centered around my knowledge, experience of over 5+ decades of owning and driving experience for all 6 Mustang generations I suggest that the 2nd generation GT350/R's will go down in Ford history as the very best overall styling, handling, braking, steering, drivers engagement and best sounding Mustang of all time therefore suggest that our cars are the "Johnny Carson" of Mustang and very unfortunate for the new 2021 Mach 1 having to follow this outstanding act.
The fact that our GT350/R's only come with a naturally aspirated FPC engine and manual transmission certainly helps solidify their position as "Best In Class" for the Mustang model.
Each to their own and bet all you want but based on the above I don't see our cars dropping in value any time soon and very happy and appreciative that I still have two examples in my corral.