The model 3...as it is right now...is still vaporware. So calling it a game changer doesn't make sense. There's still roughly 2 years to go before this car is truly available. And that's assuming all goes well, testing goes as it should, all the bugs are ironed out, changes are made and implemented, etc....
By then, I doubt it very much all the other car manufacturers are standing still waiting to see what happens.
I think the purpose of releasing the Model 3 is to generate "sales"...the orders everyone is putting in and people are going nuts over is precisely what Musk wants. To generate and create orders for a product that doesn't exist yet...except on the books.