Gundam seed Stargazer
Gundam seed stargazer was just a side story to what happend after earth got hit by astroids! It has three episodes wich are each 15 minutes long. I know because i have downloaded all of the gundam seed/Destiny/Stargazer series.
Gundam seed Astray
Gundam seed Astray is also not the third series! In fact it should not even be considerd part of the gundam seed universe because it practically was made to make money.
Gundam seed destiny movie
The third series has still not been announced and might not even have anything to do with kira or shin! However a gundam seed destiny movie has been confirmed and most likely will take place after the recent events of the last episode!
Gundam seed season 3!
Like i said before there will be another series but it might not even have anything to do with kira or shin! The directors have said that they are aiming for wherever the money goes!
I hope this clears some things up for people who dont know