At least two ways:
1. Nothing will change because people will simply say the keyword instead of typing it
2. LSI/Longtail Keywords will get much more searches, because of instead searching for "dog training", because will say "Siri, how can I train my dog?" or "what is the best dog training in xyz?"
Option 2 is much more likely to happen. Lets be honest: The most people have no clue how to use Google or other search engines. No joke, I saw it so often. Even in my family. They type in a whole sentence instead of just the keywords. Now imagine these people are going to use their voice.