Grace doesn't change anything about that for you. You still write code locally, and `grace watch` will sync you up when you reconnect.
You can't `git push` without an internet connection, either, and you can't work on your Azure / GCP / AWS resources. Or your Google Docs. Or your email. Or your Teams chat. Source control isn't a special case that must work offline, it's just that we're used to Git, and we pay the bad-UX tax of using a distributed VCS as a centralized VCS, because very few of us push to production from our dev boxes, only from a (Git)hub.
Assuming a working internet connection in the late 2020's (i.e. roughly when Git will be replaced by some competitor) is not a blocker for almost every developer in the world. And Git will still be there if offline usage is a hard requirement.