They said Luna was dead at the end of the Duscae demo as well and we know that's false. It's all still up in the air, really, even if a lot of the elements suggest this so far.
How do we know that is false? Maybe at that point she is dead. Not that I think and hope that but still. Also Regis being dead/dying would make this whole successor thing more "realistc" by bringing it to the next level. Sort of like with Garnet and Ashe.