What replaces this part of HAL?

[Tom Horsley]

I keep reading that HAL is going away, yet I have programs
that use bits and pieces of HAL, and I can't for the life
of me deduce what the "official" replacement for this
functionality is. For instance:

When my USB mouse is plugged/unplugged, I get DBUS messages
which allow me to re-run my xinput settings for the mouse
to properly configure the buttons and acceleration.

When my PTP cameras are plugged/unplugged, I also get DBUS
messages (with the HAL udi string), so I can do hal queries
to dig up properties like the USB bus and device numbers
so I can open the camera with libgphoto2.

So that's my question: If HAL really is going away, what
is supposed to replace this kind of notification mechanism
for newly plugged devices?