Also from https://x.com/LundukeJournal/status/2081376006460395685

>Over 40–60 years they have accumulated layers of patches, updates and custom logic.

>enterprise overhauls often take 5–10 years, by which time the target architecture may already be obsolete.

That seems to answer the question right there.

There's not space in the room for a bigger elephant, do the math.

Once a replacement system has been proven to have outstanding performance in testing for 10 years, then you can be confident you may just be about 25% of the way there.

Why settle for less?

Be optimistic, 25% is excellent progress in such a short time :)

I worked at the US Army ATCOM base migrating databases and programs from an IBM Mainframe to Windows 3.X using Access and SQL Server and Visual BASIC. We kept the IBM Mainframe and HP/UX databases and programs to compare to the new ones. If the results where the same, we were good enough to switch over. If the results are different, time to debug the modern programs.

I earned my stripes as a Super Debugger by fixing other people's mistakes and bugs. Sure you are going to have them, you have to debug your way out of it.

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