(Østlandets Blad - paywall) Tusenfryd forbereder seg til tidenes attraksjonsinvestering Tusenfryd vil allerede neste år komme med en ny overraskelse, men direktøren i fornøyelsesparken gleder seg enda mer til 2021. – Det blir noe nytt neste sesong, men vi jobber med noe veldig stort for 2021...
I think it was also confirmed in an article in a local newspaper, but those are a hassle to dig up as they require paywall access. I had a friend from the area show me the articles once.
EDIT to mention: The name actually fits quite well, as TusenFryd used to have a small Zamperla Dragon coaster named Dragen. It was very popular, but apparently cost more to maintain than the park was willing to pay for, so it was sold. The public still has Dragen in fresh memory, so bringing back the name for a bigger coaster would be a neat publicity stunt.
As for the involvement of Gerstlauer, I can only confirm it personally. I know someone involved in the project.