I've certainly seen my share of underutilized System p servers, but in the right hands, they're a powerful option, with features that Linux still hasn't caught up to yet. For a cool feature that I would love to see on Linux someday, peek at checkpoint-restart, which enables some really sweet capabilities [1]. Generally, anytime I hear a business tell me uptime reliability is nearly a blank-check requirement (when downtime losses are described in 5+ figures per minute and up, and it is a 24x7x365 operation), but they must still stay on a Unixen box because that is what their IT shop knows, and it's not a parallelizable application, I start looking in AIX's direction. It can be a right PITA to work with if you grew up with Linux or BSD, but once you figure out some add-ons to use, it gets much more pleasant to use.
[1] https://www.ibm.com/developerworks/aix/library/au-aix7.2.1-l...
The AS/400 (IBM i) and ClearPath are my favourites.
One with its TIMI architecture and kernel level JIT, the other with an history going back to the 60's using an almost memory safe systems programming language, while people are still debating how to replace C.
The choice to avoid risk is easy.
This is why, by the way, selling to C-suite, or above middle management, as much as it is hated in technical circles, is used. The higher you go in management, the more risk is able to be shouldered.
If Intel hypes up any AMD compatibility issues Intel can find, then that urge to avoid risk will play to Intel's advantage.