Does he even need any power to break the last seals ? They're already so fragile to the point he could broke at least one of them with his bare hands. The True Power will probably play a role in his confrontation against the Dark One since, somehow, a special link is created with him and this power always comes with a big price, so I think the Dark One might uses this against Rand. Besides it would be weird that the very seals which are keeping the Dark One at bay are sensible to his own power. Certainly in the long term since they're weakening but if it needs a burst of the True Power to get rid of it, the big bad guy would be already out no ?
Did you see one of the cover of the last book ? Seems like a huge spoil about Rand's fate, fuck !
