Hygienic macros do not require pattern-matching, as proven by the example of MIT scheme. Basically, macros in their system take three arguments - an s-expression, the environment the s-expression is being evaluated in, and the environment the macro is written in - and return syntax, which is an s-expression where you've chosen explicitly for each variable what environment it should be evaluated in. (More or less. If you're interested, it's called syntactic closures and you can probably find stuff about it online, or I can just write more here if people want.) I don't remember any way to insert a free identifier, but it might be there.
By the way, arc can already do half of that if you put (procedure? x) into literal.scm. The harder part is making variable references to things that aren't procedures, and I'm not quite sure how you'd do that (except the really annoying way, by wrapping everything in a procedure application).
SRFI-72 is another proof, as someone posted below, and might be better than syntactic closures (I don't know).
