When the Dark One said this to Demandred, I wondered what it entailed.

I believe his intent was for all the Forsaken to go forth and make trouble wherever they could. Stir the ants nest and let the Dragon Reborn kill himself in his efforts trying to fix everything that went awry. Like an american President, the Dragon Reborn would be blamed for any and all troubles, and this would make his task harder.

You see, what the Dark One was really doing was playing a waiting game. At the time he said this, the seals were weak enough that he SHOULD have been able to break free. But there was no NEED for him to do so. You see, as long as Rand Al'Thor remains sane and dedicated to fighting the Dark One, the outcome of Tarmon Gai'Don is in doubt. The Dark One MUST know the prophecies that foretell this, as well.
But what if he just waited a few measley years? He's already been imprisoned for 3,000 years, 2 more, or even 100 more wouldn't be much of a inconvenience, if it handed him everything.

The nobles of the countries that Rand controls, mostly tolerate him because they know he is only temporary, and that eventually he will die and leave them alone. But what if the Dark One didn't emerge right away? How loyal would people remain after TEN years waiting for something that doesn't look like it's going to happen? Maybe that's why the blight is as quiet as it has been. To lull people into thinking that the worst is over, or that maybe that Rand is not the real "Dragon".

Of course, by waiting, the Dark one need not fight Rand at all. Rand might go insane in that time. And then he can be taken and turned to the shadow as Egwene saw in the Ter'Angreal that was used in her test for Accepted. Both Lanfear and Ba'alzamon told Rand that the Dark One wanted him turned more than he wanted him killed.

"Let the Lord of Chaos Rule" is a battle plan of waiting, and wearing down your enemy's resources. Waiting for their vigilance to falter. By controlling the time of his re-mergence, the Dark One insures that he will be able to strike first.

This is one of the reasons Lews Therin wanted to "Break the Seals". In addition to his deathwish, he was a great tactician, and knew that it was best if you could start a battle at the time of your own choosing. Breaking the Seals would allow him to take the battle to the Dark One instead of being surprised by his eventual return.