On Stage's Frank DiLella did recently interview producers Craig Zadan and Neil Meron. They both said that they should hopefully have a draft of the script completed by the end of the summer and work from there.
I wouldn't dismiss Darren Criss for Pippin at this stage, if the mention of Harvey Weinstein at Hedwig this week was accurate. I can see Radcliffe better: bigger star, and another Zadan & Meron alum.