In a recent hotfix change, the same that added new Trading Post transmog items, Blizzard has added Trader's Tender cost to one currently unobtainable mount, the Reins of the Kor'kron War Wolf.
Originally obtained by completing Ahead of the Curve: Garrosh Hellscream (25 player)/Ahead of the Curve: Garrosh Hellscream (10 player), this mount was the first Ahead of the Curve mount. The Tendies cost is very abnormal, 7899, which is likely a placeholder. Usually we have monthly rewards with placeholder costs, like 999, but this is much higher. This is just datamining and subject to change; nothing has been confirmed or denied by Blizzard at this point.
One possibility is that the return of this mount will be tied in with the upcoming «Timerunning Pandamonium» event, coming in 10.2.7 later this year. We discussed what this event could mean in another post, which you can check out below.
Timerunning Pandamonium Speculation
The return of this mount would break a glass ceiling set in place for a decade now, which is the availability of Ahead of the Curve mounts. These mounts, rewarded by defeating the final boss of the expansion on Heroic or higher difficulty, have been a staple of the game since Mists of Pandaria when the War Wolf was added. Since then, none of them was made available outside its patch window. Allowing players to obtain one, even if a decade after the fact, would certainly shatter this paradigm and cause much debate in collector circles.