With Fererro buying up a quarter of the world's supply in hazelnuts and two thirds of the world's supply coming out of Turkey, I think a lot of farmers won't have the money to make their own spreads if they lose the Italians as a customer.
Have you heard of Ülker? Turkish brand that's way cheaper and less oilier than Nutella. If Turkey decided to cut down Nutella's hazelnut supply, there would be short term pain for the Turkish farmers but only until Ülker covers for their demand. Meanwhile Nutella would be sent scampering to reneg across its entire supply chain.