Hello HomerJ,
There is a document that was released ages ago, so the numbers may have increased since due to the nature of 64 bit storage versus 32 bit storage and the latest addition of the smart repository that allows better and more efficient storage, but the following was found in a document that has since not been updated frequently:
https://softwaresupport.hpe.com/group/softwaresupport/search-result/-/facetsearch/document/KM203228
4. How many values can List table hold and how many lists can there be?
List records are stored in the ALL_LISTS table whose primary key is AL_ITEM_ID (Data type Integer, size 4 bytes). Therefore, maximum ALL_LISTS records would be 2,147,483,647. Note that each parent can have up to 17,576 child items starting in QC 9.0.
As you can see this is an incredible amount of items within your list and these are the older standards using a 4 bit word, which may have been upgraded in newer versions which would mean item list storage entry numbers will not be an issue for you for quite some time.
Hope this helps,
Dan