Hello, elizzee and Welcome to allnurses.com and the NP forum.
Good to have you with us.
It's not the PhD that will probably be the terminal degree for the APN, it is the DNP (Doctorate of Nursing Practice).
Here is a thread with discussion about the DNP:
Doctoral degree to become an NP???
There will be Masters degrees, yes, but if the DNP becomes mandatory, all APNs will be required to obtain a DNP to practice as APN (CRNA, NP, CNS, CMN). Masters will still exist, but not for the terminal degree for the APN.