I work at a shop (a specialized provider for finance in your eyes) which still has the "transaction" workload on IBM z/OS (IMS/DB2). The parts we manage (in Openshift) interface with that (as well as other systems) and I have heard of people/seen the commits moving PL/I to Cobol. In 2021. Given Cobol's nature, those apps have more than 1k LoC easily.

We also sublease our mainframes to at least 3 other ventures; one of which is very outspoken they have left the mainframe behind. I guess that's true if you view outsourcing as (literally) leaving it behind with the competitor of your new system... It seems to be the same for most banks, none of which are having mainframes anymore publicly, but for weird reasons they still hire people for it offshore.

Given that our (and IBM's!) services are not cheap I think either a) our customers are horribly dysfunctional in anything but earning money slow and steady (...) and b) they actually might depend on those mainframe jobs. So if you are IBM or a startup adding AI to IBM I guess the numbers might add up to the claims.

One quick data point (might be not the most accurate, but I just looked into it a bit and thought I might as well share it): According to a quick look up with Sumble[0], ~120 out of Fortune 500 companies show any interest in COBOL.

Out of those it looks like about ~60 of those are actually using COBOL in-house, while most job postings from the rest are mostly "has experience with dealing with legacy COBOL systems". The top ~40 users are the ones you would expect (big banks, insurances, telco).

Of course this is a very LinkedIn/job postings lens on it, but in terms of gauging how big the addressable market for such a solution may be, I think it should do a decent job.

[0]: https://sumble.com - Not affiliated, I just quite like their product

Rule of thumb — if a bank already was there and dealing with things 30 years ago, it likely has some cobol left.

Generalizing — if the company had enough need for it 30 years ago, was big enough to but a mainframe and the thing they used it for barely changes — chances are it’s still there, if the company is still there.

Banks absolutely do have it in house, in a dedicated secure site with a fence and a moat

And insurance, and there are telcos still having boxes spinning. And places dealing with inventories or airlines and whatever, or healthcare. If databases helped and it was around before 1992 it might still be running some cobol.

This is accurate to what we've seen in the market.

If they were large enough to need compute 30-40+ years ago, they certainly have some mainframes running today. Think Walmart, United Airlines, JPMC, Geico, Coca Cola and so on.