Well, this is a bit off topic but it's the closest I could find. I'm posting here because the monorail is sort of a train, and because there was talk once about extending PATH directly to the terminals.
If we are lucky, we might see the new monorail at Newark Airport in 2026 according to this article last month. (long before any PATH extension, if that's true) https://www.nj.com/news/2021/02/new-air ... orail.html
The new monorail has been talked about for years, so I take it with a grain of salt.
On the other hand, the new Terminal One, which will replace terminal A, has been cruising right along and will open in late 21 or early 22, I've read elsewhere. The existing monorail doesn't reach it. In what seems like a 3rd world type of screw-up, for at least 4 years, and probably more, there will be quite a schlep to reach it (see the end of the article).