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.