IBM missed the 21st century turn, and buying Red Hat will probably not save everything [1].
Mainframes are just too expensive, even with open-source software running from the Canonical or Red Hat ecosystem. You just can't keep billing CPU consumption and sell memory sticks like it's made of diamonds. Running heavy "modern" workloads will give you a crazy stupid high R4HA MSU bills ... the clash between the relatively cheap commodity hardware philosophy of the last 10 years and the IBM way of billing high-end things is too big.
I would say mainframes are still really good at handling an ultra large bus with sky-high bandwidth but that's pretty much it. The power platform is a lot cheaper and also good at that.
Mainframes are just too expensive, even with open-source software running from the Canonical or Red Hat ecosystem. You just can't keep billing CPU consumption and sell memory sticks like it's made of diamonds. Running heavy "modern" workloads will give you a crazy stupid high R4HA MSU bills ... the clash between the relatively cheap commodity hardware philosophy of the last 10 years and the IBM way of billing high-end things is too big.
I would say mainframes are still really good at handling an ultra large bus with sky-high bandwidth but that's pretty much it. The power platform is a lot cheaper and also good at that.
[1] Earlier this year: IBM’s Lost Decade https://news.ycombinator.com/item?id=22224782