As per FreeBSD 8.4 9.2 and 10.0 (BETA as of writing) pkg will start replacing the old pkg_* tools, but the installed pkg command is only a bootstrapping command that downloads a current version of pkg and install it.
I like pkg, and coming from Debian apt-get and Redhat yum, the old pkg_* tools looked a bit - let's say "rough" - while pkg looks and behaves quite familiar after using apt and yum.

I was looking for bootstrapping pkg (inside a ezjail flavour) without having to hit the 'y' each and every time. I was pointed to a very simple solution:

env ASSUME_ALWAYS=YES pkg bootstrap

Sometimes it's just a matter of a) thorougly reading a manpage and b) put the pieces (switches, variables) correctly together.
Thanks Mat Arnold on this place for the right hint!