I remember considering paying thousands of dollars + travel + SF hotel to watch this last year. There's some silver lining in everyone being locked down - we can now watch all the good content from GitHub, Apple, you name, all virtual, remote.
I don't know about Github, but Apple and Microsoft have both run their major events live online for years (and at least the last two WWDCs have been streamed live by Apple in their entirety).
The really interesting thing here will be how these virtual conferences replicate some of the face-to-face aspects of the real-world conferences: labs, workshops, networking with other developers, etc. Github appears to be using this as an opportunity to introduce and trial Github Discussions, for example.