I can see giving people the option of choosing their control scheme being a thing. Select as you enter the game so people aren’t forced into a specific mode and choose when the enter into the game with their character or on the character select screen then have the ability to swap either a button keybind or in the game menu.
For example:
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Traditional = Classic Diablo experience
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Modern = WASD movement
Restricting to one or the other would be stupid but giving people the option to play the style they want would benefit people overall. I can see WASD being added but not replacing the traditional experience.