Athlon 64 came out in 2003, Pentium 4F in 2005. I'll concede that 32-bit Atoms were reasonably popular in certain market segments, but hasn't generally every consumer computer been 64-bit for over 10 years?
Sure, but the point has nothing todo with the availabilty or popularity of 64-bit CPUs. Rather, it has to do with the amount of memory deemed necessary in a computer. As far as I remember, Windows Vista, which was released into the wild just about 10 years ago, was predominantly 32-bit, 64-bit intalls, just like with XP, being more of a curiosity. Few consumer devices had more than 2GB of RAM back then.
The Athlon 64 was released in September 2003, the Prescott Pentium 4 in February 2004, and the iMac G5 in August 2004.
Desktop CPUs have been basically guaranteed to be 64 bit since 2005.
The Pentium 3 derived Pentium M and Core Solo/Duo delayed wide mobile adoption of 64 bit until Core 2 came around in July 2006. I'd guess by 2007 you could probably safely assume 64 bit across all but the cheapest laptops as well.
tl;dr: Aside from a few Atom-powered netbooks 64 bit has been standard in anything resembling a normal computer for around a decade.
Athlon 64 came out in 2003, Pentium 4F in 2005. I'll concede that 32-bit Atoms were reasonably popular in certain market segments, but hasn't generally every consumer computer been 64-bit for over 10 years?