Change of Status from H4 to F1 while waiting on I-485 approval

Need advise from gurus on the following please:

I am planning on apply for Change of Status from H4 to F1 for a dependent child who would be aging out soon (attaining 21 years)

Since the I-485 has already been filed based on ‘Date For Filing’ and interview for AOS for I-485 is complete, but waiting for PD to become current, with the current trend I doubt that the PD would be current any time soon.

In this situation, applying for Change of Status from H4 to F1 while I-485 is pending would result in rejection as the intent of immigration is already pending?