Maybe this is already possible, but so far I couldn’t find a way to do it.
To give an example: Let’s say you have a snaredrum track with a lot of unwanted hihat sound. One way of dealing with it (besides just bluntly gating it) would be to send the the track to an envelope follower (I think it’s called ‘envelope shaper’ in Cubase), and send that (with some scaling/translation function) to the automation input of an EQ (set to low-pass) cutoff control.
So far I couldn’t find a way to do this, and if it’s indeed impossible, I think it would be an awesome feature to have.
Of course there are always plugins, but besides the potential of dealing with some recording issues (like the example I gave), it would also have great potential for more creative uses. Like creating your own “Bootsy Space Bass” envelope filter using whatever EQ or filter you have available.