It is a breakthrough in some ways. Absolutely. I feel like it will be extremely useful for research and diagnostically for certain conditions. It has potential for treating certain conditions.I feel like people are underestimating the potential here. You are literally inserting a microcontroller into the brain, that we already know is capable of writing/reading data within the brain. Regardless of what it will treat, and when, this is already providing us a brand new platform for research. This IS a breakthrough. It's not a matter of if... this WILL provide researchers data we never thought possible. The brain really is the next frontier.
My skepticism is only in sound quality because brainstem implants (given to people who have had their cochlea removed), transmit sound directly to the brainstem have abysmal sound quality because they lack the tuning functions of the cochlea. Maybe the right programs could circumvent this but this is something that hasn't, thus far, been fully worked out with otoacoustic research in general and in Neuralink's own animal studies, you can't get a head start on the programming because you can't ask the pig.
I would feel better about the potential for Neuralink's hearing functions if they would address the otoacoustic challenges and how they plan to solve this because I feel otherwise that this tech is much further away for at least that use than presented and can't really even begin to be sorted out until human studies start.