I guess my definition of going nuts was a bit more conservative. Both x86-64 and ARM's AArch64 currently only use 48 bits for virtual addressing.
Still, even if you design for computers with 256GB (2^38) physical memory, you still have a virtual address space that's 2^9 times larger (assuming addresses with the MSB bit set are reserved for the kernel's memory space). This is opposed to 32 bit systems where the physical memory space is close to or larger than the virtual address space. E.g. high end smartphones sold in the last few years have 2GB RAM and only 3GB of virtual address space.
Still, even if you design for computers with 256GB (2^38) physical memory, you still have a virtual address space that's 2^9 times larger (assuming addresses with the MSB bit set are reserved for the kernel's memory space). This is opposed to 32 bit systems where the physical memory space is close to or larger than the virtual address space. E.g. high end smartphones sold in the last few years have 2GB RAM and only 3GB of virtual address space.