Global? Likely. Realtime? We're not quite that far into the future. Just try and estimate the bandwidth for the biggest security camera of all times: at 1-3 meters resolution per pixel, worldwide, that's a lot of pixels (about 510 072 000 000 000 per frame, give or take - that comes out at about half an exabyte per frame, if I'm not mistaken). Take ten of these, and you've generated as much data as the whole Internet does in a day. Oh, and you also need to store it somewhere, but this is a minor issue (in comparison to the above).