Copy/pasting this just to save it in case this turns out to be accurate, found on reddit in a deleted thread:

"Hey guys, Yradi1 here to tell you about what's to come in future Warlords of Draenor content. Ofcourse, not all content is final and some may be delayed or scrapped in the process. Both patches are going to be pretty full when it comes to content, being major content updates. Patch 6.1 is planned to contain: Tanaan Jungle Unlocked 3 New Heroic Iron Citadel Dungeons New World Boss New Garrison Outpost New Quests New Garrison Missions New Garrison Invasions Patch 6.1 MAY contain: Heirloom tab 6.2 is planned to contain: The Iron Fortress raid with 4 wings: The Primordial Stand Hellscream's Vanguard The Legion's Rest Grommash's Demise Patch 6.2 will also release Flying into Draenor, which is planned to be obtained from a new Level 4 Stables Other Level 4 Garrison buildings are not yet known. So sadly, that's all the information I've managed to scrap. I hope you are enjoying Warlords and I promise a lot of good stuff is to come!"

Translation:
6.1: Tanaan Jungle patch
- 3 new "Iron Citadel" 5-man dungeons
- New World Boss
- New Garrison Outpost (assuming Tanaan), Missions, and Invasions
- Possibility of an Heirloom tab

6.2: Iron Fortress raid patch
- 4 wings: The Primordial Stand, Hellscream's Vanguard, The Legion's Rest, Grommash's Demise
- Flying released, supposedly comes from level 4 Stables

I'm not posting this to discuss whether it's faked or just speculation, I just thought it might be worth saving for later.