When changing a VGA card in an already installed system, Plymouth will prevent
its modern (DRM/KMS) kernel mode driver to be loaded.

Example:

1. Install Leap 42.1 in QEMU using the emulated Cirrus card (-vga cirrus).
2. The system boots up with a splash screen.
3. Shut down the system.
4. Start the VM, this time with the Bochs VGA card (-vga std).
5. A splash screen will be shown, but then X falls back to the VESA driver.

As a bonus, switching to a text VT (Ctrl-Alt-F1) only gives a blinking cursor.
The VT works just fine and is usable, except the user has to operate it blindly
as no video is shown.