I didn't say Harper is like Steph...I said that it's possible that her creation is why Stephanie hasn't been around in the 52'Verse. Her curiosity and resourcefulness remind me of Stephanie and of a younger Barbara Gordon when she first became interested in Bruce's exploits as Batman. I believe she will become Bruce's "pet project" in the coming months.
I dunno. I don't see a character like Harper forcing Steph off the stage. Steph's a full fledged Bat. No shortage those on stage in the DCU. Batgirl, Batwoman, Catwoman and to a lesser extent Huntress being front and center probably have more to do with Steph and Cass being off stage than than Harper.
Pretty much everyone who catches Batman's eye is curious and resourceful.