Until and unless an item is a vanity that has been released earlier , it won't be re-released again [That's what's the devs have said previously] .

The thing with armour and helm sets is that , pretty recently we had forgotten vanity event where forerunner & founder sets vanities were available for purchase with platinum, same thing can possibly happen with the other collectable armour and helm collectables , they could also be converted into vanities in the future .