The building at the Romeo, MI address is still there, but is now "Plastic Products".
John Hanley's primary business wasn't model cars but plastic parts for the auto industry. The "Plastic Products" company at that address probably is his old company. Legend was that in later years Johan wasn't a full time concern. When ever production was needed, John would move employees from his main business over to the Johan building to crank out a run. That also explains the inconsistent and sometimes odd colors of the plastics used.
The issue with Johan kits as far back as the USA Oldies series, a lot of the cars issued were incomplete and mismatched between car, interior and dashboard. Someone said the wrong engine was in the AMX and we know that the Scrambler was really a '66 American. So they were piecing stuff together that far back.
Aside from the other kits we feel the tooling exists for, there's reasonable expectations that Okey also had molds for the '31 Caddy and '34 Mercedes, at least to make one version of each car. There were several versions of each car, (Phaeton, Cabrolet and Brougham limo on the Caddy and open and coupe on the Mercedes) but I remember on Okey's first sales list he showed a one of each car being tooled as Rat Rods.
Another comment on the tools is that the Chrysler Turbine car that Okey pressed was the promo so we know that one exists. I believe the full detail kit was a second tool and we do not know the fate.