Well, as far as I see the prestige classes are still options for player's characters (aren’t they?,) so they can still build a "Shaman Warrior" Prestige class that suits the flavour of a specific high magic campaign.
(Maybe Paizo should change the name of the class. If they call it Shaman Warrior instead of Barbarian I don’t have any objection if a character of that class can grab a thunder and fight with it...)
why don't turn "elemental rage" into a feat?