I think hair cell regeneration will be amazing -- someday. Our ci surgeon was deeply involved in research into hair cell regeneration and very positive about its benefits in 10+ years. He said that the timetable is very hard to nail down, and just his guess based on what he knew at the time. He explained to us -- almost 4 years ago -- that they thought the first rounds of treatment for hearing loss would be available to those talking part in trials in about 4-5 years (so, this year and next), and it's expected that initial efforts will provide some access to sound that approximates the early, relatively primitive CIs, and in another 5-10 years researchers should be able to at least match contemporary CI technology.
Stem cell research has been around since the '60's, with amazing leaps in the past decade. There's been a great deal of excitement about its uses for so many treatments, and I hope that hair cell regeneration becomes widely successful and possible for those who want it someday. If all goes well, no more CI surgery for many people with the type of hearing loss this addresses, and we very much hope our child will benefit form the work being done. But, he also said, there's no telling what kind of complexities they'll encounter as they learn more about stem cell biology.