Chris,

I was specifically thinking about the e-TeX 1.1 primitives \ifundefined and
\protected. Reimplementing \DeclareRobustCommand using \protected would be
such a task.

Of course, the new \mark features can be exploited by new document classes
or packages to the existing classes.

And we shouldn't forget, that e-TeX extends TeX--XeT and allows right-to-
left typesetting.

--J"org Knappen.