The initial release of TeX was introduced by Donald E. Knuth in the early 1980s. The paper is called “The texbook”: Knuth, Donald Ervin, and Duane Bibby. The texbook. Vol. 3. Reading: Addison-Wesley, 1984.
In 1986 the LaTeX extension was programmed: Lamport, Leslie, and A. LaTEX. “Document Preparation System.” (1986).
The first description of the Lyx GUI was published in a Linux journal. In contrast to TeX and LaTeX before, Lyx was not focussed on university needs but had the enduser as a target group. Quill, Ulrich. “Introduction to LyX: Make working with LaTex easierusing the WYSIWYG editor LyX.” Linux Journal 1999.57es (1999): 6. https://www.linuxjournal.com/article/1355?page=0,2&%24Version=1&%24Path=%2F&quicktabs_1=1
A modern backend for the LaTeX language itself was introduced in 2005, called Xelatex. It is basicly a pdflatex program with improved font-encodings which works fine under modern operating systems. Kew, Jonathan. “About XETEX.” (2005).
The most obvious feature in the history of TeX is the long development time. From the initial TeX release until the current software around 40 years were gone. So TeX can be seen like UNIX as some kind of universal innovation which has evolved over the time. The first version of the UNIX operating system was modified heavily until his today iteration which is Red Hat Enterprise Linux, and the same is true for TeX. The first TeX version could be started only on commandline mainframe computers. A modern recent implementation has a GUI, runs well under any operating system and produces a modern PDF layout as default. Tex itself is not very mainstream compatible, but the underlying Bibtex format is well known. For example, the WIkipedia article about Bibtex has more traffic then the article about the endnote software. So perhaps some users who are not familiar with LaTeX are using Bibtex as well?
The most interesting aspect in TeX is, that it can be combined easily with modern technology. For example, the pandoc formatter which is a markdown parser uses for it’s pdf output an underlaying LaTeX backend.
What the future will bring is easy to explain. The latest development in academic publishing is called Open Access which is on a technical side a fulltext search engine like Google Scholar. With such a search engine it is possible to find a certain paper very fast. So the future of TeX will be in online publishing of PDF papers. The arxiv project for example, is based entirely on TeX. With Lyx it is possible to extend the effort into a mass market.
The main reason why TeX was a success has economical reasons. In theory it is possible to use any other wordprocessor for formatting an academic paper for example MS-Word or Adobe Indesign. But with TeX the amount of time which has to be invested by the author is lower. That means, if the bibtex database is there, the LaTeX template is ready and the images are available in JPEG format, the final pdf paper can be rendered very easily. It is way more faster, then drag and drop all the information into a MS-Word document and adjusting manually the floating images. Sure, the TeX ecosystem is a bit complicated to grasp. But it has improved over the years and todays version of Lyx has everything out of the box what beginners in typesetting will need. The most interesting feature in Lyx is not the sophisticated layout but it is the feature to export a text into a plain-ascii format which includes the bibliographic references as well. That means, even somebody doesn’t like LaTeX he can write with Lyx nice looking pure ascii files. Left on the screen he has the outline editor, and after he has typed in the text he simply exports the file to plaintext ascii. This bypass the xelatex backend and it works quite nice.