The PC parallel
A handy proxy here is the desktop computer or PC and the hardware survey operated by game developer Valve, the outfit most famous for the Half-Life series of first-person adventure shooters.
Valve surveys users of its Steam gaming platform and the latest results show that nearly half of Steam users still have 4GB of RAM or less. On a desktop PC. In 2013. Fully 10 years since the first 64-bit PCs arrived. Uh huh.
What it all boils down to is this: there's no immediate or pressing need for beyond-4GB in a smartphone. In some very limited multi-tasking scenarios with particularly demanding apps it will probably help. But that's about it.
Instead, it's a little further out, in a future where your handset becomes your primary computing device that more memory becomes critical.
This a future where you walk into your office and your handset wirelessly and automatically hooks up to a large desktop display and powers all your demanding productivity, multimedia and even gaming apps.
How soon that will happen is hard to say. But we can see the beginnings of this transition in 2-in-1 tablet-laptop devices and the phones that morph into tablets, like of Asus's Padfone family.
Five years from now, smartphones will very likely be powerful enough for all but the most intense gaming and number crunching apps.
If that's the memory addressing part of the problem covered, are there any other benefits to 64-bit computing? Ultimately, that comes down to implementation.
Picking apart the performance gains
The shift to 64-bit offers an opportunity for chip makers to refresh both the instruction sets that define how mobile CPUs operate and their detailed internal architectures. At this point, things can get rather technical.
We could have a discussion about added register space, bigger page sizes and increased width for floating point calculations. Revisions like these are indeed due from ARM with ARMv8, which is a whole new instruction set, albeit backwards ARMv7.
ARM, of course, is the UK company whose mobile CPU instruction sets and processor core designs form the basis of nearly all smartphones and tablets available today. That includes Apple's A7 chip, which is the first ARMv8-based chip in a smartphone or tablet.
Using the A7 as a guide, early benchmarks comparing 32-bit code to 64-bit show some pretty impressive performance boosts. There are also reports of ARM's new 64-bit core design, the Cortex-A57, running as much as 50 per cent faster in 64-bit mode than the current 32-bit Cortex-A15.
Of course, the problem here is that unpicking the performance benefits that derive directly from 64-bit computing from those that come with a generational transition in CPU architecture is very tricky. But there will almost definitely be some.
What about 64-bit Android devices?
So, now we have a rough idea of the likely benefits of a 64-bit chip in a smartphone or tablet might be, when is the rest of the industry going to catch up? Put simply, what about 64-bit Android devices, set to debut in 2014?
When Apple announced the A7, the impression was conspicuously of a competition caught off guard. A senior executive from Qualcomm, maker of the popular Snapdragon chips, quipped that 64-bit was a gimmick, only to have his remarks officially retracted and find himself mysteriously demoted.
Samsung was quick to confirm it was planning 64-bit chips for its own Galaxy handsets and tablets. But since then has emitted rather mixed messages.
The bottom line is that we don't have firm dates for the arrival of 64-bit chips from Qualcomm or phones using the technology from Samsung, but the former has now announced it's first 64-bit chip, the Snapdragon 410, albeit designed for the budget market.
