He seemed to be implying 'mass transit' if that makes sense. Something that is commercially viable and available to the public. Given our past I would think and hope by the next century we have commercial space flight available to the masses. 6kmph doesn't sound too unreasonable when you think about space travel.
Can we make an object do that? Like you said, pretty easily in space. I don't know what type of things we can do with ballistics on earth at this point, but I'd guess we are very close. At least speaking by orders of magnitude, very close. I'm talking about experimental stuff, rocket sleds, that type of thing.
Can we put a human in a craft doing that?
Half to one third of that on earth? In space, probably. If we haven't already, I don't really know off of the top of my head.
Can you or I feasible go buy a seat doing that?
Maybe going into the 22nd century we will be able to.