There are plans for 64-bit kernelland with 32-bit userland, which will notably permit to efficiently make use of more than 2 GiB memory and provide 4 GiB userland addressing space.

A 64-bit GNU/Hurd is also coming soon, progress is tracked on 64-bit port! Hurd developers ported GNUMach to 64-bit some time ago. Then they started making significant progress on the x86_64 userland port in Feb 2023. As of September 2024, the Debian hurd-amd64 port works just like the hurd-i386, except for missing packages and more bugs, namely swapping issues with rumpdisk and deadlocking issues with libdiskfs/ext2fs. We are currently building 64-bit packages. We plan on supporting both a 32-bit and 64-bit Debian GNU/Hurd, only not both at the same time. However, there is no plan to fix the year 2038 concern on a 32-bit system.

That being said, you can always run a 32-bit version on a 64-bit machine, it just works, processes are just limited to a couple GiB available memory.