Does that mean Molag Bal won? "The Doors of Oblivion" described Coldharbour as a parallel Nirn, desecrated and defiled. So, if we've got a Dragon Break where all possible outcomes happen simultaneously, then that means the Planemeld worked and Molag Bal got to have his way with Tamriel, while at the same time Tamriel was saved by whatever heroes saved it and everything "worked out" in the end.

The only hitch I see is that "The Doors of Oblivion" exists in ESO as well, implying that Coldharbour was already an apocalyptic Nirn before Molag Bal's machinations. Personally, I like to think that the presence of some books "from the future" is simply a side-effect of how screwed up time is within a Dragon Break. I guess it's kinda nice that my only major gripe with the lore added by ESO is the implication that Crassius Curio wasn't the original author of the Lusty Argonian Maid.

Except there isn't anything anywhere that says dragon break.

They did explain the books on a loading screen in-game..