Ten years from now for all we know we could all have so much cheap storage and bandwidth and good, open p2p software that all coders get to archive their own full copy of github's repos. So the focus should be on getting today's job done now.
Now we have SSD which means a small one-step-backward for storage. However, we will supposedly have 10TB SSD and beyond within a couple of years which should give some breathing room.
Even with all this development, I doubt we will be able to have everything on Github locally on our computers. I imagine the typical Github project to be tiny -- probably tens of megabytes at the most so I'd say we can have all the projects that we care about available locally. One can only care about so much.
