You are of course correct that they could at any point in time decide to cancel the contracts and it's part of the political game to threaten to do so every few

You are of course correct that they could at any point in time decide to cancel the contracts and it's part of the political game to threaten to do so every few years. In practice they have few alternatives given their location as a land locked nation without the ability to feed their population without imports. All trade flows through or over territory of EU member states. Tight CH-EU cooperation has been very beneficial for both sides and most of what we see is the usual political bickering.