Mainframe-type and Power systems are still very relevant. x86/x86_64 environments are typically built to run 'reasonably' reliably with redundancy built into the software layer.
Mainframe/Power systems are built with huge RAS features - properly managed, they are not going down. Another advantage is the massive
virtualization partitioning that they can handle - you can have thousands of Linux or AIX instances running in parallel on a single high end Power server.
Yes, they are still being sold and deployed for new projects.