PCVT seems to know how to get the video back in the right mode (it
   does so when you switch to a text vt).

No, it doesn't.  It relies on the X server to do that.

This is really part of a larger problem, that the interface between
the `console' driver and the X server sucks.  In AIX there is (or
perhaps was; they were talking about removing virtual terminals) a
mechanism for the system to forcibly reclaim the terminal if the X
server became unresponsive.  This may be one of the few things AIX got
right.

Of course, this is easy to do under AIX, where the system already
needs intimate knowledge of the video adapter.  We've been trying to
avoid that on PCs because there are just *so many* different video
non-standards, but I think it's inevitable that we need to `bite the
cannon ball' some day.

Maybe we can have a default pccons-like driver, and make the
device-specific code loadable; this would allow new devices to be
`supported' without requiring people to rebuild their kernels.  This
goes along with some of my other goals; namely making the terminal
emulation machine-independent, and using mostly the same `console'
code in all of the ports.