I believe that the question whether TeX or one of its derivatives will
be used has not much to do with its capabilities or deficiencies.
People will use e-TeX (or Omega, for that matter) once it propagates
into the major TeX distributions (teTeX, emTeX, etc.).
People will use any form of TeX, if it is widely and easily available.
Complete distributions like teTeX have made major progress in this
direction. If general usage of TeX has really declined, as was
suggested on this list, then---this is my conjecture---it just means
that the non-TeX world is even better than teTeX and friends in
offering easy installation.
As important as it is to develop the core TeX and LaTeX, some
coordinated effort to improve the distribution might be even more
important for the world at large. This means ready-to-run CDs as well
as a well maintained Web interface for downloading a complete TeX.
Ideally someone who stumbles upon TeX on be web should be able to
download it for the machine he/she is on from within the web browser,
pretty much the way one can find little icons to download the Adobe
pdf reader all over the web. I am pretty sure there are many people
who would put icons "download TeX NOW!" on their web pages, if only
there was a good page to refer to...
Once this is possible, the whole question of updating wouldn't be the
(public relations) nightmare that the upgrade from LaTeX 2.09 to 2e
was (and in some quarters still is).