Dragon Master Swain production got cancelled 2 times in the past
from http://boards.na.leagueoflegends.com/en/c/story-art/vQy5EUkW-yorick-skin-where Kindlejack stated this
"Mentioning Dragon Master Swain, cancelling it, trying to make it again and having to cancel it a second time is the perfect example of why it is much worse to announce work in progress when we can't guarantee it will actually work out and ship."
This might be the best statement we can get which answers the recurring question among Swain mains and league community "What has happened to this skin concept over these years."
Just delve more deeper. I have no idea about the first cancellation but I have my guess about the second. Back in 2015 They had tried to make the skin before ChampUp team came up with the decision that Swain needs full VGUs rework or the skin team just found Swain's model and rigs very outdated to the point that they can't make the skin from it to meet the fantasy of the Dragon Master concept.
Anyway, From this Kindlejack's statement the more important question for now is is this skin concept got officially "Cancelled" or just "Iceboxed" I don't know if the Morrello's "We will do this skin - I'm sure of that" statement is something that can hold our hope now but before that his VGUs should come ASAP because no VGUs=No any new skin.