Technically those are not service account keys, so I would hazard a guess that they won't be affected, but it's still a valid concern.

Note that disabling all the service accounts will probably have unintended consequences, as they are used for all sorts of automation within Google Cloud. If you haven't created and downloaded keys for service accounts to be used elsewhere, you don't...

It's not even clear whether this will be enabled for projects that aren't part of an organization. I actually wanted to opt in early for a particular project and found that I couldn't. Some more clarity would be appreciated.