That’s assuming this child isn't the concoction of a manic ruler desperate for control. Cersei is most certainly that. Her armies are outnumbered, loyalties are dwindling, and Daenerys’s dragons -- not to mention her Dothraki horde -- are a dark and impenetrable shadow in the distance. Real or not, the baby’s an easy way to trap the gullible and lovesick Jaime in her web.
It’s also yet another way to draw a connection between Cersei and the Mad King Aerys, whose daughter Daenerys may have a fiery temper, but is still kind of heart and inspiring to her devoted. Cersei, on the other hand, is loathed and loathing, trigger-happy and prone to torture. The Mad King’s ghost still haunts the Red Keep.
The last time a Mad King sat the Iron Throne, he was slain by Jaime Lannister. Is Game of Thrones setting the stage for a similar scenario, or is it all a massive red herring?