One of the central supports against patents is that engineers given a problem will all come up with roughly the same solution. So given that Elon has dropped a number of hints the question then becomes: can a bunch of engineers come up with his proposed solution before he reveals what it is.

That's a very interesting puzzle to me and I think this may be a way in which the patent office could do their reviews: ask a community of smart cookies to come up with what is in the (secret to that point) patent application, the one that gets it right gets a part of the filing fee and the patent is denied, if nobody can crack it in some set time (say 4 weeks) then the patent is granted.