Bem -;)
1) Seu comando:
sudo apt-get remove --purge nvidia-*
Está removendo todos os pacotes que possuem a parte 'nvidia'.
Sobre o regex:
2) Você pode simular coisas:
man apt-get
-s, --simulate, --just-print, --dry-run, --recon, --no-act
No action; perform a simulation of events that would occur but do not actually change the system.
Simulação, aqui
Uma simulação, aqui, (K) ubuntu 13.04, KDE 4.10.5, eu tenho a AMD e não a Nvidia:
:~$ apt-get -s remove --purge nvidia-*
NOTE: This is only a simulation!
apt-get needs root privileges for real execution.
Keep also in mind that locking is deactivated,
so don't depend on the relevance to the real current situation!
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages will be REMOVED:
glx-alternative-mesa* glx-diversions* kde-window-manager* kde-workspace* kde-workspace-dev*
libkwinactivenvidiahack4* libkwinnvidiahack4* nvidia-installer-cleanup*
0 upgraded, 0 newly installed, 8 to remove and 0 not upgraded.
Purg glx-alternative-mesa [0.2.90]
Purg glx-diversions [0.2.90]
Purg kde-workspace [4:4.10.5-0ubuntu0.1]
Purg kde-window-manager [4:4.10.5-0ubuntu0.1]
Purg kde-workspace-dev [4:4.10.5-0ubuntu0.1]
Purg libkwinactivenvidiahack4 [4:4.10.5-0ubuntu0.1]
Purg libkwinnvidiahack4 [4:4.10.5-0ubuntu0.1]
Purg nvidia-installer-cleanup [20120731+1]
Produção total: link
Por que o gerenciador de janelas do kde será removido
O gerenciador de janelas do kde está dependendo
:~$ apt-cache show kde-window-manager
...
Depends:..libkwinnvidiahack4,...
Por que o kubuntu-desktop será removido (se estiver instalado)
O kubuntu-desktop está dependendo
:~$ apt-cache show kubuntu-desktop
Depends:...kde-window-manager, ...