As NN models get more advanced generating speech synthesis will get progressively more convincing and less expensive to implement, even if the models aren't built for speech synthesis specifically. The same can be said for image generation/transformation. If we are to continue develop AI then this is likely inevitable. There are benefits to these models for mute people, for example. Adversarial models can be built to detect fake audio samples. Regulation (ex: adding tells/signatures in commercial products) would also help. The government would have to ban most AI research or they would only be prolonging the inevitable.