Oh dear. That doesn't really sound like a good idea in the long term.
So once you place all your projects/repositories on a third party git service like Github and it goes down, what can you do to push that critical change? Might be no big deal for personal projects but unacceptable for big business and open source orgs.
You might as well call the CEO of GitHub for support. A better way is to self-host...
Even ignoring the higher cost to set up, are you sure your self-hosted solution will have better uptime? Are you sure you'll be able to get things up and running faster when it does go down than GitHub will when GitHub goes down?