The new ending, he said, is actually truer, chronologically, to the tale than the book.
Okay, so I'm guessing the film will end with the events of March 7th TA3019. That will be three days after the Battle of Helm's Deep and the destruction of Isengard by the Ents. Saruman will have been cast down, and Aragorn will be about to enter the Paths of the Dead.
On this day Frodo meets Faramir and is taken by him to Henneth Annun, the hidden camp behind the waterfall.
Failing that, it could be March 12th. That would place Aragorn somewhere near Pelargir, the Ents mopping up in Northern Rohan, Faramir retreating from Osgilliath towards Minas Tirith, Lorian being attacked from Dol Guldur (and hopefully Haldir fighting here rather than at Helm's Deep), and Frodo being mauled by Shelob.