It’s probably best to uninstall it. That said, it likely does no harm to keep it, considering you’re now using Nvidia; I would remove it anyway. If ffmpeg is in any way affected you can always reinstall that. Cheers.
Well … thats not really an end-all.
Just a few threads over is a newbie replacing mesa with mesa-git.
So tomorrow they will have mesa-git from the AUR … simply because it is from the AUR does not mean the system is not relying on it.
Of course thats not true in this case.
Just pointing out the generalization can be false.
PS
Dont use cascade for removal.
It took us years to convince pamac people to stop doing it by default…
(all the lovely examples of … users trying to remove a browser and taking xorg with it)
Please dont invoke it manually unless you know what you are doing.