Do you actually play or know anything about Fire mages?

The Fire mage rotation is actually more like the Demonology execution rotation or even Affliction (read: Shadow Trance) than it is like the Destro Rotation. You're just seeing Fire and Fire and crying foul. Fire mages stack up scorch then apply Fireball until they get 2 crits in a row, then they use an insta-cast Pyroblast.

Destro locks, on the other hand, apply the Immolate DoT, hit their Conflagrate (which requires the DoT), which procs Backdraft and gives them 15 seconds of 30% extra haste, using Chaos Bolt, Soulfire, and Incinerate.

Exactly how is that similar to ANY mage spec? Arcane spams one spell until they get a proc, then they hit another spell, then start over. Fire I talked about. Frost pretty much just spams Frostbolt and Ice Lance.

The only big change to Destruction I see coming is the loss of the Conflagrate Glyph's function. Ghostcrawler posted a while back saying that they were moving away from the idea of glyphs altering rotations, so I have a feeling we're going to see Conflagrate's glyph change somehow, and we're once again going to be waiting until Immolate is almost off before hitting it.