Hi Trevor!
Here are some alternative customers for the Viggen (with Australia too):
-The Viggen was considered by the JASDF but it was rejected for political and operationnal (lack of range) reasons.
-Belgium, the Netherlands, Denmark and Norway also considered the Viggen for the Deal of the Century, so the Dutch AF markings just make sense.
-The Viggen was also a contender in the Indian purchase where the Jaguar finally won (the Viggen was out because the US didn't want to export the engine anymore).
-Austria thought about buying the Viggen twice: first when they finally bought the Draken (the Viggen was considered as too "agressive" for a self defense force, due to some political tensions with USSR), second time when they had to replace the Draken (second-hand Viggen and second-hand or new-build Gripen lost against the Typhoon)
We can also imagine that it the Viggen won the Deal of the Century, maybe Italia could buy or rent some second-hand aircrafts instead of F-16.