In case you still doubt Black Mage's ST damage, here'd be an Astral Fire rotation assuming Umbral Hearts and cooldowns, assuming 2.4s GCD:
00.00 176.4 Fire III(Triple)
02.40 491.4 Fire IV(Ley Lines, Lucid Dreaming)
04.80 491.4 Fire IV
06.84 491.4 Fire IV(Sharpcast)
08.88 340.2 Fire I
10.92 491.4 Fire IV
13.36 491.4 Fire IV
15.80 491.4 Fire IV
18.24 491.4 Fire IV
20.68 453.6 Firestarter(Swiftcast
22.72 491.4 Fire IV(Convert)
24.76 491.4 Fire IV
27.20 491.4 Fire IV (End Fire rotation but let's continue until...)
29.64 176.4 Blizzard III
31.68 682.5 Foul(... This)
33.72 -
That's 6743.1 potency in 33.72 seconds assuming 2.40 GCD, or 199.97 potency / second. That'd be, what, 70% more than Red Mage's non-melee rotation?
So how much does this amazing melee burst by Red Mage then do?
- Corps-a-corps 130
00.00 210 Riposte(Embolden)
01.50 348+504 Zwechhau(Fleche)
03.00 564+156 Redoublement(Displacement)
05.20 638+348 Verholy(Contre Sixte)
07.60 302.4 Verstone
10.00 -
From this point on, you still have about 10.75 seconds of Embolden left, at an average power of about +7.5% over its duration. So let's add that to Red Mage's non-melee rotation's average expected pps, and we get +94.484 potency.
In total, this 10 second Red Mage burst sequence therefore managed to deal 3070.4 potency worth of damage, or 307.04 per second. But as it lasts for only 10 seconds, and considering how mediocre Red Mage's sustained PPS is while building up mana(Clearly worse than even Black Mage's Umbral Ice sequence), it's really not going to be even close to Black Mage in single target damage without some major changes to what we currently know. Especially as we consider that Black Mage's Astral Fire sequences will be far more common than Red Mage's melee sequences. In fact, for Black Mage, the Astral Fire burst is pretty much the default scenario and Umbral Ice only happens for a short period of time whereas for Red Mage the melee sequence is a very rare moment of burst and without Embolden, Red Mage has to wait for far longer to perform one melee sequence than it takes for Black Mage to perform a full astral / umbral rotation.
Well, what is there to suppose? I just use the current information we have available. It's not like I'm making it up out of thin air. The information is there.
What you could suppose is whether or not they will buff Red Mage before release, I guess. But my money's on BLM being the strongest caster, and it's not close at all. Only raid utility or major balance changes before release could change this in my eyes.