Hyper-realistic video avatars are the ultimate version and here are some examples of how the technology is progressing.
Example 1: Using a stock avatar - not great by today's standards but a year ago we would have been amazed by this.
Example 2: Made using a real financial adviser - much better
Example 3: Made using a real adviser's avatar and designed to show the range of movement possible
So they are improving all of the time and as said elsewhere within a year they will be indistinguishable from real videos. In the meantime, text based conversational AIs are the way forward.
(If you're watching on a mobile device, swipe left on the videos below.)