[swift-evolution] A Comprehensive Rethink of Access Levels in Swift

[Tino Heth]

> as ‘closed’ is a rare niche case.

If there is agreement on the importance of closed, imho we shouldn't even need variants of final:
You could already build the required class hierarchies if the restriction that a subclass can't have higher visibility as its parent is lifted.

Imho this should be done anyways, and then you could simply define an internal baseclass with "public final" subclasses.