I think that was the point of the Red Hat acquisition. "See all those Linux boxes you run? Do you want to have someone to yell at when they blow up? It's either us or Canonical.".
There's no way z/OS is going to be free or open-source (if for no other reason than if they open sourced it, you'd still need a mainframe, which means you're going to pay IBM for cloud time), so if hobbyists are going to start with something they'll probably start with Linux. Once they are no longer a hobbyist, IBM will be there to help.
> There's no way z/OS is going to be free or open-source (if for no other reason than if they open sourced it, you'd still need a mainframe, which means you're going to pay IBM for cloud time)
This is probably why IBM mainframe OSes until the 1980s are public domain: You can't run MVS without an IBM mainframe, so why bother even copyrighting the source code? The Hercules people are grateful for that bit of pragmatism.
I believe the actual reason old IBM mainframe OSes is that computer programs originally weren't copyrightable. When the law was changed to make them copyrightable, this wasn't retroactive.
> There's no way z/OS is going to be free or open-source
I never said that.
What I said is that there aren't any onboarding routes to z/OS (or AIX, or IBMi). You either already are running one or more z/OS boxes, or you'll just deploy to cloud, CentOS, Kubernetes, OpenShift, on commodity CPUs (x86 and ARM), or any of the other stack that rivals a mainframe in some capabilities (and carefully avoid business requirements only a mainframe can fulfill)
There's no way z/OS is going to be free or open-source (if for no other reason than if they open sourced it, you'd still need a mainframe, which means you're going to pay IBM for cloud time), so if hobbyists are going to start with something they'll probably start with Linux. Once they are no longer a hobbyist, IBM will be there to help.