Regarding Diablo 3 for Switch, there were concerns that there would be a need to subscribe to the Switch Online service in order to partake in Seasons in Diablo III: Eternal Collection. However, Blizzard has now clarified that will not be the case.
I see there’s some confusion about the necessity of the Nintendo Switch Online service in relations to the upcoming Diablo III: Eternal Collection. To clarify, access to playing Seasons does not require a Nintendo Switch Online subscription. However, access to online multiplayer does. This is identical to the way gameplay features function for the Xbox One and PS4 versions of Diablo III as well. Hope this makes the situation more clear!