The US space program has the following unmet needs:
- Something to lift very large objects into space, i.e. a heavy lift rocket similar to the payload capacity of a saturn V rocket.
- Some sort of mobile work platform in space for missions such as repairing the hubble telescope or building Infrastructure like the ISS.
- Some form of 100% reusable space transportation system, where fuel and chemicals are our only real operating costs (no throw away fuel tanks or boosters)
I list the heavy lift rocket first, because that remains our biggest lacking capability since the 1960's. If we had a true heavy lift rocket available, not only could we orbit much larger and more capable satilites, but we could orbit larger manned habitat segments up to twice the size of the US Desteny laboratory in the ISS. We need that capability for a variety of reasons if we ever intend to go after the helium III reserves on the moon, or attempt any form of asteroid mining and refinement in space, or spaceborne manufacturing.
The mobile work platform is necessary to save costs. there are thousands of satilites in orbit now, and many of them are ageing faster than we are replacing them. The shuttle fleet in the past served an active role in service and maintaining some of those more important satilites. We also need something we can use as an "anchor" for assembly of larger structures in space. None of the designs presently on the books for the various smaller startup companies that the Obama administration is looking to for spacee needs come even close. A scaled up Lockheed X-33 might be able to fill that role, but a SSTO system is going to be limited in payload capacity.
What we really need is some form of duel stage to orbit system, where an airbreating mothership takes a rocket to the edge of the atmosphere and then launches it. Similar to spaceship one in design, but much larger and capable of a much greater initial launch velocity. Nasa again has had designs in the books for several of those since almost the second the shuttle was launched. but we don't build them.
I like FalconX as a company. I don't see them being able to create a true shuttle replacement with equil or greater capabilities in the next 30 years. Boeing and or Lockheed could build such a craft, but tney probably won't.