I am not sure a transmorg system is in the works, but in case it isn’t planned, this would be an alternative.
Make a sub section in the store skin section and put all available armour pieces in there. I think many players love these skins, especially lower level ones.
Make them cheap, nothing insane, while same time starting a log in reward system. If a player logs in something like 20 days of the month - they get 10 store currency at the end of the month.
Make those skins cost 10 store currency each, so players can either start collecting skins they like via log in reward currency (or save that currency up for something else, if they so wish), while players who wish to buy store currency, can collect as many as they like without having to save up.
Could of course offer the skins as log in rewards themselves, with an interface where players can choose a skin at the end of each months.
These skins have to remain dyable, same as they are as the original armour.