Whilst it might be theoretically possible to design such a tethered structure, in practice no materials currently exist with the necessary tensile strength... even carbon nanotubes would fall somewhat short of what would be required. If a way could be found to produce the current favoured candidate material, carbon nanotube fibres (ideally single-walled from a mass point of view) in sufficient quantities and with sufficient lengths to be woven, braided and bound into a tether with the required mechanical characteristics there could still be potential problems such as the likely electrical conductivity of such a cable.

I'm not dismissing the idea per se but the quoted Japanese target of 2030 would seem a little optimistic given current technology.