With the Viewing of the dark hand and Callandor, with the fact the Dragon as now tried the True Power, and is linked to the Shadow, with the fact Shai'tan has infused Shaidar Haran and in a limited way can now interact physically in the Pattern through this 'hand"... it seems very likely Callandor's role at SG is not something that it could have been used for in the AOL.

LTT wasn't short on strength. He seemed to have been missing saidar to reinforce the weaves, and the greater precision brought by working with circles. The quantity of saidin at his team's disposal doesn't appear to have been a problem at all.

Callandor had been discovered as flawed anyway. Unless used in a circle with two women, it offered no protection against drawing too much. To use it by himself, a man would need extreme self control, probably difficult to maintain when holding so much OP. Rand behaved very erratically each time he used Callandor.

In the WOS there was yet no taint, so the fact it magnified it too would most likely have gone unnoticed until the early Breaking. My guess is that the team who made the EOTW, and also had secured Callandor, might have been those who discovered it now magnified the feeling of wrongness on saidin.

That it magnified the Taint suggests Callandor would interact in an unexpected way with the True Power.

One idea might be to use Callandor to bait Shaidar Haran to use it to break Shai'tan's prison. My guess is that Shai'tan might try to enter Creation (ie: break his prison) by passing through Callandor. Perhaps he would have to release his grip on the Bore to do that, and the interaction of the three ta'veren being One might give enough to the Wheel to "heal reality", that is to reknit the Pattern without this hole in it. The way to destroy Callandor, where part of Shai'tan would be trapped, would be the SL taint, ie: Fain. He and the sword would annihilitate one another, as happened with Mashadar and the Taint in WH.

There are tons of possibilities, really, but it seems to me almost certain that if Callandor isn't a red herring and will be used at SG, it won't be to provide Rand with a powerful circle of three.

Right now, Rand's is still caught with the same crippling problem faced by both Latra Posae and Lews Therin. The only solutions they can conceive of to seal the Bore involve touching Shai'tan/the True Power directly with the One Power. That interaction is massively risky, dangerous and can have unpredictable results. LTT's perspective was that that it had to been attempted, for lack of any other idea. LPD's view was that it was better to build a doomsday device with the power to destroy the world, and with it ward a giant area to remove Shai'tan's touch on the world, while scientists wracked their brains out to find a permanent solution to remove the Blight. My guess is that if Shai'tan managed to reach out and touch those wards, the effects might have been differently but equally or even more disastrous as if LTT's plan went wrong.

In any case, it appears the Wheel couldn't let the Dragon seal the Bore as he planned to with both saidin and saidar, and it could not let Latra Posae's plan be implemented as well: both doomed the world.

The solution was to let LTT go forward, but to deprive him of the women, and to delay him long enough so the devices required to Cleanse saidin down the line could be be built. Once done, the possibility to use the two CK together was removed, and with Rand's epiphany the male one got destroyed, removing the possibility a single male channeler could destroy Creation, now that the Dragon had made his final choice that it was worth saving and he accepted his role as the Creator's tool and champion, perhaps even a fairly limited avatar of a kind, or a vessel, to oppose Shaidar Haran as Shai'tan's.