
The Zelda Timeline
Kotaku is reporting that the upcoming Zelda art book (an officially licensed Nintendo product) contains the actual Legend of Zelda timeline.
Note that the “split” is due to Ocarina’s time differences and assumptions based on different ways that story could have ended and branched off from his two ages: the Link to the Past split is Link failing, the Majora’s split is Link defeating canon and branching off from his boyhood and the Wind Waker split is Link defeating Ganon and branching from his older years.
So, yeah, that suggests not only alternate universes, but two parallel universes spinning off the same single outcome.