- Spend $1.5 million maintaining the current system, but as bits get updated keep in mind the system that you'd like to have in 10 15 years time.
You're going to have to replace the system within 300 years anyway, you aren't saving that money, every feature you add that is reliant on the old system is literally technical debt, because eventually you'll have to rewrite it for the new system.
I'm not even saying you need to have a new system in mind, just keep in mind that you will be moving to a new system, so code appropriately.
And it will still be able to run all your programs that were written and tested since the late 20th century, by the kind of organic entity we used to call "human".
Slightly more serious retort: I'm not aware of any brands from 300 years ago, I'd be surprised if any of IBMs customers survive, let alone enough to keep IBM as a going concern.
Btw when you start folding the space time mesh, terahertz figures just become marketing numbers, what you really want to know is how many parsecs it can do the Kessel run in.
You might be, you just don't realize that they're hundreds of years old.
For example, the insurance company Lloyds of London is fairly well-known around the globe. It's 333 years old.
If anything, this is a sign that mainframe users have way too much profit for what should probably be commodity software.
- Spend $300,000,000 over 10 years moving to a new system, and hope that by the time you've done that it's not obsolete.
- Spend $1,000,000 a year on a system that still works.
You could run the system for 300 years for what it would cost to replace the system.
In spite of the collective wisdom on HN, there aren't a lot of companies in the world with hundreds of millions of dollars sitting around doing nothing. Even ones that work on mainframes.