Since I work with deaf children, the CI issue has been debated at my work and I do see a lot of anger and fear from people. I wont go into the details but if 90% of deaf babies are being implanted and the parents decide to put their child into the mainstreaming programs at their home school, then it means the closings of the deaf schools due to low enrollment and as a result, many jobs will be lost.
Well, there could be some element of truth in what you say; Still, I don't think the CI is primarily responsible for the diminishing returns currently being experienced at state-supported Deaf schools everywhere.
By far, and the #1 reason why Deaf schools' enrollment #'s are declining, is simply because of better advances in medicine. This factor alone, I'm guessing, has reduced the overall incidence of Deafness by more than 50%. And BTW, this is a good thing; I would never wish for more Deaf people to be born, nor wish Deafness upon anyone else.
Couple that phenomenon with the increasing trend towards mainstreaming, and you pretty much have a lethal tide, which pretty much has eroded state-sponsored Deaf schools' 'beachheads'. (Ok, I'm going overboard with analogies here!) Maybe with further advances in the CI technology, increasing Cued English usage, etc., all could very well be the final nail in shuttering Deaf schools all over. (If the medical community ever perfects stem cell technologies in curing Deafness, all bets are off!)
Like you, I pretty much have ambivalent feelings about this; I want ASL to continue, and have Deaf culture alive and vibrant well into my old age. Time will tell, and markedly illustrates how we need to truly appreciate what we have now, and enjoy life being a Deaf person immersed in Deaf culture.