VCA Faders are great for adding automation without loosing the ability to go back and change static levels.
It would be great to be able to „link“ a VCA Fader not only to the volume level, but also to a send level. The first great thing would be to have a chosen send level as fader, especially when working with motor fader controller. On top, you would be able to automate send levels in addition in a „non destructive“ way, so the basic send level and the fader of the fx can be left unchanged or even reworked, if you go back to tune the static mix.
For example you can send -6dB from your main vocals to an delay FX channel, that also gets some sends from other vocal tracks. For the static mix, you would tweak the sends and the overall volume of the FX channel. The you would automate the delay send to emphasize some parts. If these changes could be made on top, you can go back and change the overall send level for the vocals to e.g. -7dB without the need to move all automation points and with a fader instead of the pc mouse.
I can imagine that this could already be done using a group channel in between the send and the FX channel. This applies to VCA in general, though.