Talked today with Chuck Ghilani, Penn State Wilkes-Barre, at the PA Conference about the single SPC datum for PA. Currently it is just an annual student project for his students to each define an new SPC system. He does see that it is probable such a PA single zone SPC could occur in conjunction with the NAD 2018 datum.
Today Dave Doyle said words to the affect that NAD 2018 would be centered at ITRF 0,0,0 with a different ellipsoid from NAD 83. Not sure if it would match the ITRF ellipsoid.