I think it would be cool to see a real time EQ Matching plugin. It would be like the Izotope EQ which takes a reference eq from a desired sound clip and creates curves that bring the source audio to match the reference clip (intensity adjustment included).
In Fab-Q 3 there is a similar function.
None of these EQ matching plugins offer the ability to make real time “learning” adjustments as source EQ could potentially change. In the live context this could be caused by proximity variation or other kinds of variations.
I get that going to far with this would be un-natural. I have seen great results from some degree of eq matching though. If it were to to be able to track with the source audio and adjust in real time that would be one very interesting plugin.