All the benefits of deep learning (natural language understanding, context, engaging answers) make this ergonomically possible and not able to be replicated using symbolic AI. It's frankly irrelevant to the discussion right now and will at best imho only play some part in the overall process. If attributable sources are important, I think it's way likelier that a deep learning approach will be used. But I think for most queries answered by an AI this will not be important since they will be trivial and I expect for the rest you switch to the normal search behaviour to be able to trust your source.