Last Tuesday the battle for Darkshore began. That is part one, this coming Tuesday part two will start. As far as I understand, at the end of part two, the mounts are rewarded. @Lucky posted HERE with a blue post about the mounts. I have linked the Wowhead guide to The War of the Thorns.
Do the Darkshore dailies while you can folks, get the gear upgrades and learn your new specs, BFA is almost here.