My main has had JC/LW since I created him back in WotLK, but I didn't use LW much during WoD (I've got like 2k+ burnished just collecting dust in my bank) and from looking at Legion crafting I don't anticipate using it much in the future either. Seems like the crafted mail gear isn't really practical to max out due to crazy high material costs, and I certainly wouldn't use the base level of it.
My thought is to replace LW with Mining, to support the JC. Can anyone think of a good reason to keep Leatherworking?