Googling Kevin Holleran produces little substantive information. Some Slashdot commenters have expressed skepticism that anyone could develop the wealth and influence that Holleran appears to have without having left a significant Googletrail. The man is, in short, a cipher.
"There is clearly no “there” there – just your anecdotes about chatting with some rich UK investor and your shuttle pals and the (apparent) fun of being secretive about all of this. No one has produced any prospectus, summary, brochure, etc. that describes what this company was proposing to do."
"MLD you and the other Shuttle-huggers just won’t let go will you? This whole idea was a joke and calls into serious question the skills of the investors you claim were involved."
From comments on NASASpaceflight, the Holleran business plan appears to require a "Shuttle-capable" vehicle. It's not clear what that means. Chris Bergin of NASASpaceflight (better placed than most to comment) says that "it's not about the upmass", so whatever it is, the intended purpose isn't something that (say) Falcon Heavy on its own can do (easily). Presumably, we're looking at one or more of the following: a reusable aerospace vehicle with manned capability, a large internal payload bay mounting an RMS and able to function as an orbital workbench, manoeuvrable on orbit, and with significant down mass and cross range.
So, what particular business case do they have in mind that requires an STS-class vehicle and isn't dependent on NASA?
* Heavy payloads
Bergin says it's not about upmass
* Upvolume = physically large payloads (STS payload volume is somewhat larger than standard Falcon Heavy)
Surely it must be cheaper and easier to tweak the FH design to have a longer fairing than build an entire STS from scratch?
* (Commercial) station assembly
STS is nice to have, but it's not clear that it's necessary. Complex multi module stations can be assembled without an orbiter-class vehicle. See: Mir.
* Satellite servicing
CCDev vehicle with a work platform and/or a robotic satellite servicer would be cheaper.
* Microgravity experiments/in-orbit manufacturing
CCDev vehicle and a Bigelow free-flyer, or DragonLab would be cheaper.
* Debris removal
Bergin says no. Delta-V requirements can be challenging anyway. Kind of thing better handled by robotics or remote effectors (e.g. laser pushbrooms).
* Human-tended assembly of satellite solar power systems in LEO, then transported to GEO by electric thrusters
Maaaaybe, but wouldn't it be cheaper to get them to robotically self-assemble?
* Large-scale orbital passenger transport ("Moonraker module")
If you can make the business case close for an orbital space liner, then the very best of luck to you. If your system is based on legacy Shuttle hardware, you're going to need it…
In short, I'm kind of scratching my head as to what they want it for that's a viable market in the near term, that isn't better addressed by something else.
The Buran orbiter 1.02 'Ptichka' is reportedly 95% complete, and sitting in a warehouse at Baikonur. It's hardly been touched for 20 years, with unknown consequences for its flight-worthiness. Would also have to retool and rebuild the entire Energia production line, which wouldn't be cheap. The consequences for certain sections of the US press ("They got a Shuttle and we don't!!!!!111one") would be amusing to watch.
The HL-42 is a 42% scale-up of the HL-20 lifting body (currently being reborn as the SNC Dreamchaser). It doesn't have a payload bay as such, but can be fitted with an external module for servicing and supplementary OMS capacity. Could also serve as an orbital space liner.
Venturestar has a payload bay. Maybe they think that improvements in materials make the composite hydrogen tanks viable? Would have to go through the X-33 development programme (again).
DC-X/DC-Y/DC-1: Now this *would* be cool, though technically very challenging to reach orbit with net positive payload.