Linux is moving more and more towards a very
hybrid kernel, that is looking more and more like a microkernel. It
already does several things that we already do, user level file
systems and drivers for example. It already does several things that
we would like in GNU/Hurd as well, USB support, sound, petabyte
support for filesystems, ext3, ..., the list goes on.
If your point is that using GNU/Linux systems is useful, you need
not argue this. I already agree with you. However, they are not
the GNU system. They are something different.
Meanwhile, as long as people are interested in working on the Hurd,
let's keep doing it.