@Jean-YvesPochez today, if you know how to program and maintain an AS400, you can make big $$$$
even if the product is out of sell for so many years...
While IBM stopped selling the "AS/400" many years ago, they started selling the "iSeries" then the "IBM i". Hardware wise very different different from the AS/400 and predecessors, but still software compatible. And therein lies a crucial factor. Many enterprises have a huge investment in software that literally spans decades of development, and newer IBM i hardware is cheap and fast compared to iSeries or AS/400 or S/3x hardware.
There are still shops installing brand new IBM i models -- I personally know of one who has a new install scheduled just a few weeks from now.
Emile: And while there is a COBOL compiler available, relatively few shops used it unless they started with IBM mainframe instead of midrange equipment. Mostly it was done in variants of a language IBM first invented in the '60's for use with card-punch based systems -- Report Program Generator (aka RPG) -- but the modern variants used in current IBM i models have little resemblance to the original language.