Imagine you are a CIO. You have mainframe apps. Everything I said is true of your existing solution. If you keep it as is, it works just fine for the foreseeable future. Every other way forward requires a total rewrite of systems that have been stable for years and are typically mission critical financial and transaction processing systems.
That's what I mean by IBM having a compelling offering.
There are advantages to the mainframe, but there are disadvantages too. As a CIO your job is to consider both.
Even if you say "March 14, 2021 is the grand final feature freeze for the Mainframe, and day one of the Cloud Initiative", it's not going to happen. You're not going to have a MVP for several years, and a full replacement for five million undocumented lines of COBOL for even longer. Production fires will have to be fought. Regulators will demand you change something, and won't be keen to hear "we're supporting it in the Cloud Initiative, which customers will see in 2025." So you're gonna be writing quite a few more cheques to IBM and your team of COBOL jockeys.
After 5 or 6 years, as you've unloaded most of the customers to your painstakingly built replacement, you can finally begin to scale down the mainframe staff and perhaps return/downgrade some of the rented hardware.
Given that, it may be less a put-your-own-head-in-the-guillotine move just to spend those years hiring in a few new graduates with the promise of "We'll apprentice you to handle our unique and obscure codebase, and as long as you show up 40 hours a week and don't take a dump on your manager's desk, you're going to have a reliable paycheque for the next 20 years."
My understanding is at least Java is well supported on mainframes. It's not the latest greatest language, but it sure beats ALGOL.
Then Algol, COBOL, RPG, NEWP, PL/I.
Which ones has it discontinued? I thought once the 360 platform got going, it was basically forever (unbroken chain of compatibility). What am I missing?
Maybe if you are using zos without any niche configuration. IBM has discontinued many mainframe platforms in the past, and there's no guarantee that next year they won't approach you with a 10x markup on your renting costs, that will become 50x in a couple of years and will keep going up until you decide to stop paying.
> yes, it will scale with whatever transaction volume you need in the future, because that's what the mainframe is for
Only if you gave-up on data dependency from the beginning. Transactions here means independent data processing, with possible rollbacks, not the relational concept people got used to on databases. If one needs relational data, it won't scale. NoSQL can scale with non-relational data too, it's not an exclusivity of mainframes.
> yes, you can get 99.999999999999999% uptime, because you have reliability built into the platform in astounding depth
That one is ridiculous. Uptime is limited by business code bugs, network and power outages, integration problems, and well, all that causes 90% of the downtime on a single-server shop. All the mainframe promises is that the hardware won't be a problem.
> yes, we'll happily help develop new functionality and support your in house staff in managing this system; the mainframe can actually detect faults and arrange a service call.
Yes, mainframes come with support contracts. You can get support for other platforms too, with the advantage that you won't need to hire IBM.
Anyway, none of that changes the fact that nobody wants to start using a mainframe nowadays, and that the people using them are either looking on how to replace them or avoiding increasing their usage. IBM will certainly be able to milk that market over the medium term, even more if they keep increasing their prices. They revenue may even go up for a while. But that's not thriving.