The glyph gives them a lot of flexibility to change spells around to make the tanking viable. Part of me wonders, however, if the glyph may be their way of testing out a fourth spec for warlocks since, as was mentioned, the glyph effects quickly become a wall of text. This could be their way of doing a fourth spec without making any promises. It also provides a way to see how people choose to use it in the beta and get feedback without committing to anything. If they drop it from the game, they dropped a glyph - not a promised 4th specialization. I think Blizzard would be reluctant to take away one of the dps specs since many people out there love demonology dps. I like what Blizzard seems to be doing with the warlocks - they are working hard to give warlocks an identity beyond "the dot class" and make each of the specs feel interesting and unique. At the same time, they are making rotations more straightforward. Making four specs may lead to difficulties distinguishing a dps demonology from a tanking demonology, but affliction and destruction seem to have a feel of their own that doesn't make you think "mage with lots of dots." They also seem to be giving a nod to all those warlocks from past versions of WoW who were ranged tanks (due to high survivability and threat generation abilities) and giving us tools to execute it without it feeling like an exploit.