I have no idea if wearing a cone for an extended period of time at her age will have any effect on her ear development, but I don't see how it could. I will say that some dogs go through a "conehead" phase and some don't - Sneaker was one of those whose ears came to a point at the top of her head when she was young (and we actually called her conehead!), and her ear set was totally normal once her head grew into those ears. None of my other GSDs (4 total) ever had ears that did that - they did all sorts of other things though! Dena & Keefer had much smaller ears as puppies, more proportional to the size of their heads at the time, so it all kind of grew together at a similar rate.