I would argue that it's really only toy projects that can continue in an Internet outage. "Serious shops" will be using cloud based version control, cloud based testing workflows, and most likely cloud based distribution of the software. isn't it only the little side projects you can get away with not needing the Internet for? Software long ago stopped being something one person on a computer did, today the professional SDLC includes many tools that are hosted.

Do farmers still plough fields with a Horse just in case their tractor runs out of diesel? Of course not, as technology moves on we all have to accept the inherent risks in exchange for the huge benefits, otherwise the work you do will be too slow and your job taken by someone willing to leverage the tools available today.