Hmmm I wonder. There was a mention at one point in a live letter iirc that the ilvl should stop ~150/160. I expect by end of the 3.0 story the avg ilvl will be 120/130 - with lvl53 being ~90.
My thinking is: job and main story progression - for job. You start at i50 or so with your AF so jumping up by a ton of ilvls makes little sense.
But at the same time I think the full main story will be needed to actually hit the expansion story - so since current highest ilvl for main story is i90 you get exp from getting to that point in the story and thinking about it you would hit that level at around 52/53 most likely. Yes I actually think our current gear won't become worthless on expansion drop. But will be starting gear to the expansion endgame. But at the same time I think it might slow down the ilvl creep to 2 or 5 ilvls - maybe even to the point that not all gear will be the same ilvl but more various like during leveling.