Lame as **** if true... They can't have much faith in the movie, or they were surprised at how good this Jerome guy is.
They didn't have to kill him off though. They could've at least left it open ended with him presumed dead or banged up in Arkham or something. It's not like he had to return in the show - as much as we would've liked to see it.
Saying that, while Jerome was great, and as decent as his origin story was, I think it was too early for him to be there anyway. It's gonna be at least another 10-12 years or more before Bruce dons the cape, and in pretty much every telling of Batman, Joker is more a reaction to the Bat, not the other way round.