Draenor Set
Azuremyst Isle - 1 to 10
Bloodmyrk Isle - 10 to 20
Eversong Forest - 1 to 10
Quel'thalas - 10 to 20
Hellfire Peninsula - 58 to 62
Zangarmarsh - 60 to 64
Terokkar Forest - 61 to 65
The Deadlands - 63 to 67
Nagrand - 64 to 68
Blade's Edge Mountains - 66 to 70
Netherstorm - 67 to 70
Shadowmoon Valley - 69 to 70
- Northrend Set
Borean Tundra - 67 to 70
Howling Fjord - 67 to 70
Dragonblight - 69 to 72
Grizzly Hills - 70 to 73
Crystalsong Forest - 72 to 75
Zul'drak - 73 to 76
Sholazar Basin - 75 to 79
Storm Peaks - 76 to 80
Icecrown Glacier - 78 to 80
- Maelstrom Set (Cataclysm)
Gilneas - 77 to 80
Grim Batol - 78 to 81
Kul Tiras - 79 to 82
Kezan - 81 to 86
Tel Abim - 83 to 85
Zandalar - 84 to 87
Plunder Isle - 86 to 88
The Broken Isles - 87 to 90
The Maelstrom - 89 to 90
- Plane Set (Emerald Dream)
Pandaria - 1 to 10 (pandaren, alliance)
Hiji - 10 to 20
Wolfenhold - 1 to 10 (????, horde)
Xorothian Plains - 10 to 20
The Green Lands - 88 to 91
The Dying Paradise - 91 to 94
The Emerald Nightmare - 94 to 97
The Eye of Ysera - 97 to 100
Deephome - 88 to 91
Skywall - 91 to 94 i guess blizz decided to move these into the Cata expansion
The Abyssal Maw - 94 to 97
The Firelands - 97 to 100
- Legion Set (Burning Legion, last expansion?)
K'aresh - 96 to 99
Argus Meadowlands - 97 to 100
Mac'Aree - 99 to 100
Maw of Oblivion - 100+
The Burning Citadel - 100+++
This was posted a few years ago after the launch of TBC on some unofficial forum, and it seems they were right, they predicted WLK, and now Cata as well, judging by the rest of it, we have 2 more expansions, which will be related to the Emerald Dream and the Burning Legion.
In the expansion after Cata, alliance will get Pandaren, horde will get some demon race (maybe dreadlords? satyrs?, who knows)
*the texts in italic are notes writen by me
/discuss