Port this to the web and you will have the most advanced online word processor by far

I guess this depends on what you mean by "most advanced". TeXmacs combines the easy learning curve of Emacs with the familiar word processing paradigm of TeX to form a program usable by 1/10000 of the market. Sure, it's advanced. So's the flight deck of the Airbus A380.

A more successful interpretation of "most advanced" would be "gives the user the easiest interface to use to accomplish his tasks". By that standard, I think Google Docs or Writeboard is much more advanced than TeXmacs.