Not rely on any gnome/gtk libs. Pure QT/KDE networkmanager would be great.

What do you mean by "not rely on any gnome/gtk libs"? I am pretty sure that NetworkManager is desktop-agnostic and does not relay on any specific GNOME/GTK+ library.
Here are dependencies of network-manager package on my system (Debian Wheezy):
libc6, libdbus-1-3, libdbus-glib-1-2, libgcrypt11, libglib2.0-0, libgnutls26, libgudev-1.0-0, libnl-3-200, libnl-genl-3-200, libnl-route-3-200, libnm-glib4, libnm-util2, libpolkit-gobject-1-0, libuuid1, lsb-base, wpasupplicant, dbus, udev, adduser, isc-dhcp-client

I don't see anything from GNOME/GTK here.

Maybe you mean GLib? Well, it's not GTK+/GNOME library. Yes, it used to be and started as such. But then developers decided to split all GUI part out of it. You can read more about it on Wikipedia.

And Qt can't really replace GLib in NetworkManager, because Qt is C++, while GLib is C. That would require to rewrite NetworkManager in another language. It might be sensible (I am not in position to judge), but we have NM written in C right now and it does work, so why change this?

Maybe your system pulls network-manager-gnome (or similarly named package) as dependency of NetworkManager? If so, then this is clearly fault of package maintainer, not NetworkManager itself.

On the side note, I praise KDE for overcoming NIH syndrome and putting much effort into using cross-desktop standards and technologies. Fragmentation has harmed Linux for so long, that any initiative to stop it and provide more unified environment is desired.

In terms of GUI, KDE ships a component it calls "Network Management" through it's Extragear component, which virtually every distribution using NetworkManager should include if it ships KDE.

The application "nm-applet" is the GNOME application you might be referring to here - and it does have heavy GNOME specific dependencies.