Just so you know i spent the last year working in an environment with more redhat on power and aix on power then x86. They have power8, as well as z13. The power decision was purely political the actual enterprise architects wanted to move it all to redhat on x86.
IBM does a good job of getting open *ix stuff cross compiled and it mostly works. But anything Microsoft (obviously) , any cloud services automation (azure stack, Vrealize, etc), there are lots of issues with middle-ware even for stuff that is well supported on power like Hana. Your standard document archive solutions (objective, trim, etc), unified communications,etc the list just goes on and on, if it wasn't midnight i might indulge you more.
Honestly in an average enterprise workplace how much as a percentage of x86 do you think you could drop in replace with power? Now how much of a standard enterprise could you drop in replace with Zen?