It had more to do with Microsoft not having 64 bit Windows for Atom CPUs ready earlier. Existing recent Bay Trail tablets like the Dell Venue 11 Pro have 64 bit CPUs but 64 bit was turned off. They said they'll enable it in a BIOS update. For more consumer-facing brands and models, it's less certain if the manufacturers will bother since average Atom-buying end users could care less about whether they're running 32 or 64 bit, and RAM is soldered on so it's not as if you could upgrade to 4 or more gigs on existing 2 gig machines.
-------------------- Lisa Gade Editor in Chief, MobileTechReview