Are there any current discussions about switch to a different standard directory hierarchy for Linux? The only thing I currently know of is GoboLinux, which looks quite outdated.
I wouldn't say FHS is dead. The 3.0 version is documented to be still under development, although it is quite possible nobody is currently working on it.
FHS 2.0 is relatively well respected by most Gnu/Linux distributions, but ignored by other Unix like OSes.
I guess one of the reasons FHS 3 has some trouble being released is it is very difficult to reach a consensus between distro maintainers about what should be on the file system and where. Any change might break existing commands that expect files to be located somewhere.
That's probably why the POSIX standard is very light on that area, and only mandate a very limited number of files and directories to exist,
The Linux Foundation is responsible for maintaining the Linux Standards Base which refers to FHS as part of its standard. I have located a 3.0 standard draft You can follow their FHS Tag. I have no idea what's actually going on with this, but I wouldn't be surprised if some of the recent developments have been caused by this.