The Seanchan did gain channeling but the attack also served as a catalyst to reunite the Tower and root out the BA. I find it hard to believe that it will ever be that ripe for destruction again.

 

Right, but the Seanchan does not know about that.

 

And the tower does not know that Elaida can Travel, hence they will not be prepared.

That's not true, a lot of people in the Tower, including Egwene, know that Elaida can Travel.