As I expected, it was the case of Microsoft store jumping the gun and putting pre-order page up before AT&T. So, now this page stands taken down. But, in a statement sent to Computer world, MS has said that any pre-orders submitted for the Lumia 1520 and flip cover accessory which also went on pre-order at MS Store after Lumia 1520, will be honored.
It seems that insider tip was right. Lumia 1520 is now on pre-order at MS store (First week of November) and the on-contract price is $199 indeed. The device will ship from 15th of November as indicated by the pre-order page. The off-contract price is sweet $549 and you can pre-order the device now. Surprisingly pre-order has not begun at AT&T so someone has either jumped the gun at MS store or may be AT&T will also open the pre-order soon.
Thanks Ahmed29 for the Tip. Cheers!