> test depends: to specifically mark those dependencies that are only
> needed for when the pkg is being tested; effectively ephemeral
> build/run time depends that go away once testing is completed.

Does that mean that USE=test is going away somehow?

Also, could you please stop spreading FUD with your examples? A quick
glance shows that what you have expanded there, a fairly reasonable
Gentoo dev will solve using:

RDEPEND="..."
DEPEND="${RDEPEND}
    ..."

So if you really want to show some advantages, please compare it with
*real* code.

-- 
Best regards,
Michał Górny