[PlutoIsAPlanet]

Not on the system as you'll likely break ABI compatibility and need to recompile everything that uses glibc (basically everything), and LTS distros (e.g. CentOS, RHEL, Ubuntu LTS) guarantee binary compatibility during the release so this isn't feasible.

[dTal]

Would it actually break though? It's my understanding that glibc attempts to preserve backwards compatibility, such that binaries built under older versions will work under newer versions. As far as I know it's not a hard commitment the way it is for the kernel, but breakages are infrequent.