Wow, what an enormous challenge to be facing.
I have no personal experience with this, but I do have some professional knowledge that may be helpful. Take this for whatever it's worth to you, because every individual and every family is different.
- Look into whether your son is a good candidate for a cochlear implant. Last time I checked in on this issue, insurance companies would only pay for an implant in one ear. Your son actually sounds like an ideal candidate, because one ear is clearly worse, and because that ear doesn't benefit from hearing aids. (An implant destroys the hair-cells in the ear, so you can't go back to a hearing aid, but if a hearing aid already isn't useful . . .) Your son is also a good candidate in that his hearing loss has been progressive, so he presumably has had at least a few years of near-normal hearing for his brain to learn speech sounds. People like that do better with "learning how to hear" with an implant than people who are pre-lingually deaf.
- Consider getting your son some exposure to sign language. He can continue to be primarily a spoken-language user, but sign language will give him an extra set of skills and access to an additional community that will give him a sense of support and connection as the years go on. Many "oral deaf" kids, even those with excellent speech skills who thrive academically, discover the deaf signing community in adolescence or young adulthood and are amazed at how easy and comfortable communication can be. Often they are very sad and angry that they weren't exposed to it sooner.
- If you do go the sign language route, avoid "signed English" communication systems. They are clunky and artificial, and the brain does not process them as natural language. Go for the real deal -- American Sign Language (or whatever the indigenous sign language is in your country).
- Also, be prepared for a lot of dis-information about sign language from medical professionals. Particularly if you go the implant route, you may be told that you must not expose your kid to sign language, because it will interfere with his progress with spoken language. This is completely untrue, and I would quietly ignore it. (True fun fact: among congenitally deaf people, the ones with the best English skills are deaf people with deaf parents who grew up with sign language as literally their native language. Obviously doesn't apply to your case, but it goes to show that there is no conflict between the two.)
Wishing you all the best!
