So we're all rooting for hyperloop to have test tracks in 2015, demo tracks in 2020, very limited real-life deployment in 2040, and sure to become inter-city mainstream reality sometime later? Some think we'll be on Mars by then ;)

I somehow think that if people wanted it, it would come faster than 2040. We're working towards fusion power faster than that!

If people wanting it made technology feasible, we'd have had flying cars in 1990

If it's technologically possible, economically profitable, and people want it, then. Flying cars have difficulties this doesn't (seem to) on all three counts.