It seems reasonable (and possibly low) for a 90 days estimate to extract the content from the variety of versions of static page, structure it, and then publish it in a more modern fashion.
It's all very well to say they should have used a more efficient system from the start, but "the start" in this case is 1996, which is the wild west in terms of best practices.
Publishing a page is running content from a CMS through a templating system. However, the time spent executing templates isn't the only factor in the duration of the "publish". The slides refer to a compilation step (which actually also included a preprocessor step), and includes delegating to a service to copy the resulting page to disk and ensure the write succeeds for all data centers. For data consistency and system monitoring, we essentially treat that entire process as an atomic action and wait for all parts to finish. Additionally, since "publishing" is a core process for us, we avoid doing massive publishes that might risk the systems involved in the successful publishing of current articles. So increasing the number of these for the sake of pushing code is considered too risky. Yes, there are ways of mitigating that risk, but dealing with this legacy problem once and for all is a better path forward than scaling up this solution.
I am not attacking what they were doing, my point was that this is an issue of delaying the move to a template based system way longer than necessary. I am speculating on whether they did move to some templating, but not all the way, and wondering what exactly they were using before that.
Saying "static HTML files" is well and good, but it doesn't explain how they were created. By hand??
Also, saying "90 days to republish" seems to be suggesting some process they have in mind besides manually scraping the data out. If you have 1 million random files, scraping could easily take years not 3 months. It would be interesting to know what process they are suggesting to follow in those 90 days. My speculation is they did use some sort of outdated CMS software.
Focusing on shifting all "rendering" into front end JS seems like it will lead to more difficulty in the long run instead of using a more efficient structured page creation mechanism.
I am curious how the static pages were created. Others here are speculating that templating was not done. If not; what does "republishing" mean exactly?