JCGUY wrote: The extension could cement EWR as the premiere gateway to lower Manhattan (where the PA owns some real estate if I'm not mistaken).
Yes, the PA does own real estate in lower Manhattan, as well as in Jersey City (Hoboken waterfront). Yes, I also agree with JCGUY that getting to EWR from lower Manhattan can be rather confusing. Also, having a direct link to EWR would be great for both lower Manhattan and Jersey City.
My two cents:
Giving people too many options could be a bad thing. Think about it, some people can't tell the difference between NJT and Amtrak. To add a third rail option into Manhattan from EWR has the potential to create a nightmare. The one option, one ticket idea works for those who are
not familiar with the region. Those who are savvy and seasoned will find the best/convenient/cheapest route to their liking.
The extension (either PATH or AirTrain) itself doesn't look likely to happen, the idea has been kicked around for awhile, but I have my doubts it's ever going to get off the ground. But, if it were, the legal work needed to acquire property and rights, plus potential public opposition (See LIRR Main Line 3rd Track, MNRR Hudson Line expansion) may kill it outright.