The laws of supply and demand will make sure that there will always be people available to maintain those systems. The price will go up until some 'modern' programmer is tempted enough to open a 3 decades old book on COBOL and JCL.
Your understanding of business is flawed, businesses are advancing by marketing, not by shacking up with every new hot tech that comes along in favour of their old, trusted and reliable tech.
The larger, older and more profitable a business is the more likely that they are going to be ultra-conservative about using new technology at the core of their business.
Eventually we'll get rid of this stuff but I wouldn't bet on it happening in the next two decades, unless someone finds a way to emulate a mainframe on a cluster with similar reliability. And then we still need to get rid of the software.
Your understanding of business is flawed, businesses are advancing by marketing, not by shacking up with every new hot tech that comes along in favour of their old, trusted and reliable tech.
The larger, older and more profitable a business is the more likely that they are going to be ultra-conservative about using new technology at the core of their business.
Eventually we'll get rid of this stuff but I wouldn't bet on it happening in the next two decades, unless someone finds a way to emulate a mainframe on a cluster with similar reliability. And then we still need to get rid of the software.