The announcement of a Netherdrake flying mount in the next patch was a beacon of hope to broke people like myself, who hoped we could quest for the mount while continuing to blow our hard-earned cash on epic gear and new recipes. Unfortunately, our hopes were in vain. The Netherdrake quest line apparently requires 300 riding skill to begin.
Andrevv of World of Raids provides a nice guide plus screenshots of the quest line, which I'll summarize here. First, you have to swear yourself to the Netherdrake faction (which requires doing the Kindness questline for neutrality.) Then you get asked to disguise yourself as a Fel Orc and join the Illidari! Awesome! I always wanted to be Illidari. You then head out to Netherwing Ledge and get a couple of quests as an Orc. You can either gather 40 of some special ore/herb/etc. if you have a gathering profession, or pick up 40 crystals if you're not. Then you can head over to a goblin mercenary, who will give you some quests to help the Netherwing faction by sabotaging the Orcs. You can gather fel glands to poison orc peons or collect Netherwing relics from a skyway.
There's no information on where the questline goes after that, but the ore/crystal/poison questlines are marked as "Daily," and Andrevv got 250 Netherwing reputation for turning in his first 40 ore. The Daily quests seem to be meant to limit the amount of grinding you can do in one day -- but since there are screenshots of PTR characters with drakes already, this may not be working as intended.