The tragic but most likely outcome of this debate will be: most people just won't care, they will continue to buy and use Apple hardware as if nothing happened. The average consumer does only hear about the idea of protecting kids and approves this noble goal. Most consumers just do not care about the consequences this can have on their privacy.
If people would really care about their privacy, Facebook and Instagram wouldn't be as big as they are, nobody would use facebook messenger for communication and a lot fewer people would use Windows and Android. Despite the warning of privacy advocates, experienced users, etc, people don't seem to care and I doubt this will change with the CSAM debate.
I could argue that this actually might be different since Facebook and Instagram is opt-in. I think regular users understand that if they willingly upload a picture to a social media site, even if it is in a DM, it _might_ be "hacked", so you can choose not to upload that how-the-fuck-do-i-look-naked-from-behind mirror selfie and be completely confident that no-one will see this (cloud sync off). But now, if the general public will find out that every photo you take, period, is "analyzed", maybe people will start choosing otherwise. I think we will have to see.
On could argue that this is scanning is also opt in, it requires you to purchase an iPhone. Also, at least according to Apple's provided material, the scanning only affects images which are uploaded to the iCloud, so not every image on the device. However, how long that restriction actually holds once the system is in place is questionable. Also, the risk of abuse by authorities as well the fact that there is no way to monitor the system as a user is a huge part of the problem.
If people would really care about their privacy, Facebook and Instagram wouldn't be as big as they are, nobody would use facebook messenger for communication and a lot fewer people would use Windows and Android. Despite the warning of privacy advocates, experienced users, etc, people don't seem to care and I doubt this will change with the CSAM debate.