Trish was indeed a suitable candidate, but what happened tonight had purely been happenstance.
The appearance of the Dark Knight had long been decided on.
Now that Batman couldn't suppress the criminals anymore, the second generation master had to take the stage.
Then, when Joker started making big news, it would make sense for him to clash with the second generation master.
Both of them needed to establish their own personas first so that they wouldn't draw suspicion when they started fighting for real.
But nothing major had happened in New York recently, and the Dark Knight didn't have a chance to shine.
Furthermore, the personality of this second generation master was to keep a low profile. He shouldn't squabble with the "martyred" Batman and tarnish his standing. It was a good choice to start with the media.
