How many namespaces and databases could be in one InterSystems IRIS installation?

to my understanding, there is no technical limit.
Though I believe to remember that it used to be ~16.000 some time in past.

Class SYS.Database maps to ^SYS("CONFIG","IRIS","Databases",<DBNAME>) and has NO  limit there

similar Namespaces are stored in SYS("CONFIG","IRIS","Namespaces",<NSPCE>) an are covered by %SYS.Namespace

If there is any limit it must be related to internal memory structures.  (gmheap ??)