This reference almost slipped past me...

[Yrusama]

Does this mean there will once again be potions and spells that grant invisibility or anti-sound buffs to evade aggro?

Interested to learn more.

While I can't speak for the devs, I'm not going to expect any sneak/invisible items or abilities available to anyone except gatherers, at least not immediately. Many of the forum reps also work on the Final Fantasy XI forums, and it is likely that Fernehawles has at lease played FFXI and knows that we will get a joke in reference to those items because many of use have played XI as well.