My best guess as an uninformed lurker and a Keybase user is that it's too early to know. You would have to know what's the impact of "sunsetting" features and for that you probably need more than 180k early adopters.
In case of chat you can always fallback to Telegram (I've done that after trying to move people to Wire).
In case of git you can always move the repo.
With the setup that's there now I can see how it could be used as the main origin along with a push to GitHub hook. Pull requests would be even mergable (blessed be Torvalds), though I'm not 100% sure if GitHub would pick up on that and autoclose the PR.
In case of chat you can always fallback to Telegram (I've done that after trying to move people to Wire).
In case of git you can always move the repo.
With the setup that's there now I can see how it could be used as the main origin along with a push to GitHub hook. Pull requests would be even mergable (blessed be Torvalds), though I'm not 100% sure if GitHub would pick up on that and autoclose the PR.