Spells! Spells...spells...spells!

[Alkar]

They did do away with them yes, for now.

But there is nothing stopping them adding them in again, there still in the game after all.

It doesn't make sense to add a scaling system to replace tiers and reintroduce tiers later on. This system is much better and we can actually use lower level spells even if only to power up the others.
In FFXI there's no point in using lower level tiers when you get the higher ones, that's a slot that could be assigned to a useful spell that doesn't become obsolete.
So no, tiers aren't coming back unless they remove the scaling system... which isn't likely.