I agree with with the part about learning the native spoken language around you and I do think that cued speech is useful as an lipreading aid and as an aid for understanding phonics. Personally, I think it'd be more useful for postlingual deaf children though I do not know of any research pertaining to cued speech and postlingual deaf children. I also should point out most hearing don't know cued speech.
However, it's also not realistic for someone who has language delays to gain native fluency in spoken language, it is realistic for them to gain enough fluency to be understood by others. Many deaf don't like to write notes to the hearing as they know they don't write well. Nor is it realistic to expect all deaf to develop good speech. My ex bf is quite literate but he has no oral skills at all.
I also should point out we can't completely assimilated even if we don't know sign because it is harder for many of us to keep up with the hearing's constant chattering.
