They won't. There was a post a week or so ago where somebody went on the PTR and spent 500k nethershards to see what sort of chance at a legendary you could get from them, and they didn't get a single item from the ToS loot table. (Which was a pretty flawed test since they continually recopied over the same character, so it wasn't a single batch of 500k, but that's neither here nor there.)

Relinquished tokens ONLY pull from drop tables that are ilvl 880 and lower. ToS LFR starts at 895. People keep saying they pull from the Broken Shore world boss table, and they drop 900 so that must mean they'll pull from ToS. The Broken Shore world boss loot tables are actually 860 and items are auto upgraded to 900. This was done probably so the Relinquished tokens could grab from their loot table.

http://www.wowhead.com/npc=121124/apocron

http://www.wowhead.com/npc=117470/sivash

http://www.wowhead.com/npc=117303/malificus

This could POSSIBLY change, but it hasn't this whole PTR cycle, and I wouldn't expect them to change it last minute either.