Federated learning would be amazing for medical data. It has hard to get data out of hospitals, so training models locally and merging them is a nice feature.
Of course, one has to make sure the training data cannot be inferred from the model.
PySyft will also (soon!) have features for Differential Privacy built in as well - which will facilitate making sure the model doesn't memorize things (technically it's an upper bound)
Of course, one has to make sure the training data cannot be inferred from the model.