My personal theory is that:
01 to 15 are reserved for nuclear carriers.
16 to 30 are reserved for conventionally powered carriers.
31 to 45 are reserved for LHDs.
46 to 60 are reserved for LHAs.
The first Chinese nuclear powered aircraft carrier will get the number 01.
Hypothetically somewhere later in the century, if China had already built 15 plus conventional carriers, decommissioned and started to replace them with a new class, once it is part the number 30, it will wrap back to 16 and the number counts upwards again.