Use Tokens and/or Replacement Patterns in Shortcodes
Ok, seems there are some limited ways to do this, using available replacement patterns that are not contained within square brackets. i.e. %1 and !1, but not [replacement pattern]

Luck would have it, the replacements I need are the %1 and !1 values.

Still - would be great if anyone had any ideas how to use square bracketed replacement patterns in shortcodes without closing the shortcode (which is what appears to happen).