At this point there is an error in the pkgbuild of numix-circle-icon-theme. We will show you that you need to delete an obstructing file and rerun upall.
sudo rm /usr/share/icons/Numix-Circle/icon-theme.cache
We are also delete packages that were orphaned. I means that nobody is maintaining them.
sudo pacman -R b43-firmware b43-fwcutter
We see that the brand new kernel of 31/12/2018 4.20 is coming in so we reboot.
There is also a lot of Plasma and Qt5 elements coming in.
Do not be afraid if this will crash your system or if this will make your system act up.
Just reboot and evaluate then.