Yes, the O series is 2500 pieces.
We have seen Panerai in a way, being put in a situation when they can't really win. We were talking about what would happen to the price of the 372 if they had limited it to 300 pieces
In many ways, the 372 is a gift to the enthusiast, anyone who wants one can readily get one, and I for one, personally hope that it remains a regular production in the years to come.
Cheers!
TC