In 7.3 we are going to Argus. If any of you haven't read this comic from before legion's launch I highly recommend it ( https://bnetcmsus-a.akamaihd.net/cms/content_entry_media/io/IOBVHZGUWSES1469116501571.pdf ) because the last page is where this idea comes from.
I didn't think much of it at the time, but now that we know we are going to Argus it starts to line up.
We are taking Velens ship to Argus, we aren't just teleporting there – This means there will be legitimate time passing as we go to Argus, it's hard to say how much time, I'm not sure if they ever revealed how long it took them to go from Argus to Azeroth originally.
Given how OLD Anduin looks in that picture, I'm going to guess a time skip of 35 years will happen (it could be more, but maybe Draenors cinematic of 35 years also hinted towards this?). That's a lot of time to skip… so I half wonder if we will get a second raid on a 7.4 patch to help push this time skip across, or if that 35 years is ONE WAY, so a round skip back to Azeroth would be 70 years.
If the latter ends up being the case than our characters age itself HAS to come into play, because this expansion has a big focus on your character in the story. Put simply, we would just be too old (doesn't really apply to undead…. but that's their problem to solve) when we returned to Azeroth, and with so much time passing, the world of azeroth could of assumed we all died, the world could be drastically different, etc.
It would be interesting to see how they did another expansion if this was the case…. people talk about WOW 2, if they ever could/would do it… but it would certainly be a good time to do it if it happens like this, or perhaps WoW itself will evolve into what we would consider WoW 2?
Regardless, it will be interesting to see how it all plays out.