What happens to our iLevels?

[Gyson]

Before someone jumps in with "WoW did this, so XIV will be the same," Yoshida said in his PAX interview with Famitsu that current gear will not be replaced as soon as you hit 51. So while 135 gear will probably be replaced by the time you hit 60, I can't imagine it happening immediately, especially since the MSQ only requires up to 90.

Which is exactly what WoW does. If you have some of the *best equipment available prior to the launch of an expansion* in WoW, generally that gear will be better than most of the gear you obtain during your trip through the first 4-7 new levels of the 10 available.