My 2¢ on this topic:

1. org is an excellent tool for writing.  I cannot consider writing with
   any other tool these days.
2. texi is an excellent tool for reading/browsing
   documentation.  Likewise, I cannot imagine doing so in another tool
   (in the Emacs sphere).

We should find a way to allow the manual to be written in org with the
manual ready to read in info.

As a user (and sometime contributor in small ways) of emacs over the
past 35 (!) years, I would hate to see it ossify again as it did during
the 90s.  We must move forward and nothing should be cast in stone in
terms of development, whether for code or documentation.

If this means, as suggested by somebody along the way, that the result
is an increase in the building time for Emacs, I think this is a small
price to pay.  I would venture to guess that >99% of Emacs's users are
not building their own version but simply installing the binary for
their systems.  And I'm sure that even for those that build Emacs from
source, when testing new code, could be given the choice to build
documentation or not.  That's what makefiles are for...

In any case, thanks to all involved.  The effort that *all* of you in
this thread put in day in day out is highly welcome and much
appreciated!

Thanks for listening.
-- 
Eric S Fraga via Emacs 27.0.50, Org release_9.1.6-191-g90607d