I REEEEEEEEEEEEEEEEEEEEEALLY hope they don't drop from LFR because they (Blizzard) swore a thousand times we wouldn't have to go into LFR.
If they DO drop from LFR, at LEAST make it so that you only get them from LFR or N/H/M (e.g., if you clear 7/7N/H/or M every week, you don't have to do LFR)*
* How this would work: If you kill 7/7N and 7/7LFR, you'd only get one set of stones. If you then did Heroic or Mythic, the same boss would drop stones again. Basically if you do LFR, you have to kill the same boss 3 times in a week to get stones twice.