BibTeX has many shortcomings but apparently there was (at some point) a plan to develop BibTeX 1.0 with the aim of overcoming at least some drawbacks.
See this paper by Oren Patashnik, the author of BibTeX. However, that paper is from 2003 (!!) and, unless I'm missing something, the plans never materialised. The latest version of BibTeX seems to be 0.99d from 2010.
Now I realise many TeXperts consider Biblatex+Biber the modern alternative but BibTeX still ships with every LaTeX distribution and many journals/publishers use it. Surely there cannot be much harm in improving the default bibliography system that ships with LaTeX.
Is anyone aware of why BibTeX 1.0 was abandoned? Or was it? Finally, and this may be naive, but could there be value in putting BibTeX on, say, github.com/latex3 for people to consider contributing to it?