Although kids of HKID holder who already become canada PR or canadian citizen when the kids was born do not have the ROA (Right of Abode) in HK, so cannot get HKID card and HKSAR passport and 回鄉卡.
But they still have the ROL (Right to Land) ie. They can live, work and study in HK. Just that they cannot vote in HK.
So, in reality, it doesn't really make much difference. Just like the PR and citizen status here in Canada.
Also, after living in HK for 7 years, they can get the ROA back.
Please see previous posting from Hairball for further details.