From the bill.....
β(E) LIMITATION IN SERIES TO DECEASED PRESIDENTS.β
No coin issued under this subsection may bear the image
of a living former or current President, or of any deceased
former President during the 2-year period following the
date of the death of that President
β(8) TERMINATION OF PROGRAM.βThe issuance of coins
under this subsection shall terminate when each President
has been so honored, subject to paragraph (2)(E), and may
not be resumed except by an Act of Congress.
So perhaps they will skip Carter and end with Reagan.