Oh it will probably be implemented sometime.
Mainly due to all the whining about people picking the wrong AC (as if its hard to level up a new toon to where you pick your AC).
BUT, when it is eventually released (which, i hope, is no time soon), i forsee a wave of QQing and nerdrage on the forums because A: It will cost CC (buuuhh, subs should have eeeeverything free), B: Morons will not realize that almost all their gear will become useless (especially the ones playing AC's that have different armour types) and C: People will whine because they whine about everything nowadays.
As a sub, I'm okay with the advance class change costing CC. As a sub, still not okay with the dye packs.
So obviously, you're mistaken, and subs can see the differences in various things.
I also fail to see how advance class changes means "become the new FotM"
That's more like to be a change up between classes, and less likely (but not impossible) to be a change in one's advance class.