I'm hoping they'll eventually introduce something like the Nexus Cape from XI... teleport to party leader's location (or nearest home point crystal or zone line)

As for the clues about the timeline... if I remember right, several of the trailers covered it. Recall a voice over stating "5 years have come and gone...", you watch scenes from around the realm as narration talks about how the realm has changed, "...an adventurer arrives in Eorzea...", and then you see the party teleport in. At the very least, it strongly hints at what happened to them. They've been edited in the current release of the game, but I think the progression was retained in one of the videos that runs when it goes into attract mode if you sit idle long enough.