Topic Bonus rolls in 5.4
Did they announce how will it work? Will there be new kind of 'coins'? And what with coins for ToT LFR once SoO is released? It's kinda hard to find it going through all the things they have announced.
Warforged Seals will be obtained the same way as Mogu Runes were (weekly quest, exchanging for Lesser Charms). Cap of 10.
Mogu Runes will have a cap of 20 (up from 10, to bring them in line with Elder Charms)
Mogu Runes will be obtainable from the Timeless Isle:
"The Timeless Isle is inhabited by all manner of strange and powerful creatures that will test the mettle of solo explorers, but great rewards await the brave and skillful: epic loot, bind-to-account gear, Mogu Runes of Fate, pets, mounts, fun toys, and much more."
According to the comments above, you can buy them for 2500 Timeless Coins. More info at: http://ptr.wowhead.com/currency=777#comments
Of course, until 5.4 goes live, things could change.