The Python 2-3 transition and some developments after made it definitely not so boring for me, but hopefully it'll be more stable in the coming decades ;).
"Cannot live without" is a strong wording, but software that I use a lot and that's mature/stable in my experience: shell (zsh, bash, sh), GNU utils, vim, nmap, xfce, git, ssh, mpv, Xorg, curl, and lots of little old CLI tools.
"Cannot live without" is a strong wording, but software that I use a lot and that's mature/stable in my experience: shell (zsh, bash, sh), GNU utils, vim, nmap, xfce, git, ssh, mpv, Xorg, curl, and lots of little old CLI tools.