Debian GNU/Hurd uses the same repositories; it just uses different binaries
from those repositories. Incidentally, I'm sure most proprietary software is
only available to Debian as GNU/Linux binaries, but there are a minority of
programs that have their source available under a proprietary license (I know
of such a program under CC BY-NC, for example). Any such programs in the
Debian non-free repository can be ported to GNU/Hurd, and if they are, Debian
GNU/Hurd users will still come across it.
I don't know whether or not the Hurd is able to load firmware blobs. But if
it is, then firmware blobs loaded by Linux could be loaded by the Hurd, too,
and in that case it would be likely for Debian's distribution of the Hurd to
be built to do this with firmware from the non-free repository.
In summary: don't expect Debian to be without all its problems just by
switching the kernel to the Hurd.
