Alternatives

You dismiss Emacs and others as "not the future" too readily.  You should not be as interested
in the future so much as in the past.  Specifically, you want to re-use libraries and code.
But you decide to reinvent some of the more painful parts.  That seems to be a long-running
trend in programming, and I wish it would end.

Hotwire seems really cool, but I (for one) would greatly prefer seeing the effort go into
extending and perfecting an existing system.  Some of the benefits you list don't apply to me;
I already *have* re-usable pipes and buffers in Emacs, process and directory editors, image
thumbnails, and an interactive D-Bus interface.  And a mail and news client, document viewers,
web browsers, debuggers, and more.  Not everything is perfectly integrated, but that's a
byproduct of so many years of success.

As your list shows, Emacs isn't the only other project that could use your effort and vision.
It is unfortunate that you decided not to help any of those.

(And xterm has a GUI portion also: the Tektronix window.  It's been there a long, long time,
but few programs still can use it.)