In the unfortunate event that he does not live to see these plans come true, is there anyone who can take over to fulfill them? Either inside or outside his group?

Burt has some very bright people working for him but do any of them have the skills to pull it off? I honestly don't know. There's another aspect - would Paul Allen or Richard Branson be willing to back ($$$) Scaled without Burt? They both know and respect Burt. They might not have the same confidence in his successor. No matter how skilled or creative Burt's successor turns out to be, the company will succeed or fail based on their continuing to win development contracts. Some of that is personality driven. I can only hope that Scaled continues to succeed like Lockheed's Shunk Works did after Kelly Johnson retired, but it's by no means a sure thing.

For that matter, does Burt have the skills to pull off his dreams? As Gary has pointed out, hypersonic aerodynamics is different and reentry design is a huge engineering challenge. Burt's shuttlecock mode would probably result in a big lump of molten slag when reentering from orbit, much less from the moon or beyond. I've followed Burt's career for over 30 years and have tremendous respect for him, but that doesn't mean that he's a lock to be able to design and build workable orbital spacecraft. However, I wouldn't bet against him, either.

As for others outside of Scaled, I don't know enough about the other companies to say. Tom knows more about them and might be able to answer your question.