What about macOS Sierra? will it get some kind of security update for adressing Meltdown - Spectre?
The Apple root bug is completely different from Meltdown and Spectre. These bugs are in the processor handling of elevated privileges, and so were OS-independent. That is why Linux, Windows, MacOS and iOS were all having patches sent out in the past week. Core parts of the OS are being modified to remove the impact of these processor bugs. The extent and impact of these bugs is dependent on which processor you have.AFAIK, the bug was introduced by the 10.13.1 patch to High Sierra, so the issue does not apply to 10.12 Sierra users.
FYI the NVIDIA driver is out, at least for some.... I am post 10.13.2 (17C88) --- TY Tonymac!