Since we are fantasizing here, I would prefer large tubes underground and magnetic lift on coaster style rails that can get me around the world in minutes. Since we have those tubes, we can run fiber optic cables along side them. Until then, I will stick with video conferencing. I am too grumpy to sit in a plane more than two hours.
In China, the largest high speed train network in the world, current technology's realistic speeds for realistic routes work out to around 200km/hr against an 'as the crow flies' distance (reference: recent 6 hour journey). This is actually very competitive with flying by the time you've done the 'get out of town' and 'security theater' parts, then the 'get back in to town' part for sort of 1000-2000km distances. After that, it's better to fly.
