I would love for a few banks to dump all their old COBOL code on to GitHub. Not because it would necessarily be useful for anything, but simply because it would be fascinating to read... There is actually very little open source COBOL code available, of the massive quantities of COBOL code written over the decades the vast, vast majority of it remains closed source.

Sadly I think a lot of it is just going to be lost to history... at an old employer of mine, I remember we had a store room full of old 9 track mainframe backup tapes – the mainframe had been retired and we no longer had a 9 track tape drive to read them with – I wonder if they are still there now – ideally they'd be sent to some sort of archive – they couldn't be released now without vetting because they would have contained confidential information (e.g. employee payroll information, customer data), but a century from now when all of us are dead who cares if our confidential info gets released to the public then?