The Future...

64-bit processors are almost inevitable.
Linux currently works well on Alpha, UltraSPARC, and 64-bit MIPS.
Groups are working on support for other existing 64-bit CPUs like PA-RISC.
Other groups are working on upcoming processors like AMD's Sledgehammer and Intel/HP's Itanium/Merced/whatever-it's-called-this-week.

64-bit processors are almost inevitable.