"Three prominent nebulae dominate the Skyrim heavens – the thief, the warrior, and the mage. Each of these represents one of the three master skill sets. Each nebula houses six constellations, each of which represents a skill."

No mention of any other constellation except the ones relating to skills. Where does it say all the birthsigns are still there? Bethesda is preserving the player’s ties to star signs by making the individual stars that make up each constellation light up when the corresponding perk is selected.

“When you glance to the sky after you’ve played the game for a while, what you’re seeing in the sky is different than what somebody else is seeing based on the constellations,” Howard says." Pretty clear on how the system works, and the way it will affect the night sky itself.

Again, no mention whatsoever about any additional constellations of birthsigns, in my opinion.