Just want to tell you that the start of Oblivion would be 3E433, not 3E453 as in the recently released FAQ. There is a mistake in the A Brief History of the Empire. Check this thread for more information. It makes the Oblivion starts after 6 or so years after Morrowind events.
That's not certain yet, but I expect the Third Era to end during Oblivion (probably with the Emperor's death). On the other hand, things like ends of eras are often decided retroactively, so we might not find out the exact date until TES V.