CentOS Linux is gone (CentOS 8 reached end of life at the end of 2021 and CentOS 7 followed in mid-2024), and CentOS Stream is not a like-for-like replacement. The two real successors are AlmaLinux and Rocky Linux, and since 2023 they no longer work the same way under the hood: AlmaLinux targets ABI compatibility with RHEL, Rocky holds 1:1 binary parity. This guide explains what actually differs between them now, gives a conditions-based verdict instead of "it depends," and walks the real migration paths (migrate2rocky, almalinux-deploy, and ELevate for the CentOS 7 cross-major jump), including the pre-flight checklist, the inhibitor wall, and the rollback plan.