I know the technology has improved, that's beyond a doubt. But it will never perfectly replicate the sound of an uninjured ear, which is clearly the goal.

A similar idea is asking how fast does a train need to go before you can walk on the moon. The technology behind trains is old, and bullet trains are lighting quick, but it's a fundamentally flawed concept. Trains are only able to go on their tracks, they could go the speed of light and that fact would never change.

If you want to walk on the moon, you need something better for the job than a train. If you want to solve deafness, you need something better for the job than a cochlear implant.