If you're using a Lumia 950 or 950 XL with a relatively modern Snapdragon processor (namely, a Snapdragon 808 or beyond), then your hardware is fully capable of running a 64-bit operating system. That would pay dividends, potentially at least, regarding processing speed, security, and a host of other advantages. To date, though, Microsoft's Windows 10 Mobile has been 32-bit, limiting the advantages that could be attained from 64-bit computing.
All of that is likely set to change at some point in the future. As we reported earlier this year, there have been hints that Microsoft would enable ARM64 support in Windows 10 Mobile. ARM64, just as it sounds, is the 64-bit architecture that ARM implemented in the Snapdragon 808, 810, and 820 (and will be the architecture used in their mainstream SoCs going forward).
Today, Microsoft News published a story extolling the virtues of engineer Dave Cutler, who's decades-long career had a profound impact on the technology industry and on Microsoft specifically. Buried in that story was this bit:
Cutler stopped managing the entire NT project in 1996 but continued to lead the kernel development until 2006. In March 2005, he completed one of his “most gratifying pieces of work” at Microsoft when, partnering with AMD, he helped develop the AMD64 architecture (64-bit extensions to the 32-bit x86 architecture) and led the effort to ship the first two x64 64-bit Windows systems (workstation and server). At the time, some questioned why Microsoft developed a 64-bit system; today most computers are 64-bit systems and even our phones will soon have a 64-bit operating system.
While this doesn't provide any more specifics, certainly it seems to confirm that in one way or another, Microsoft phones will run some version of a 64-bit OS. ARM64 is the most likely candidate, and our money is on the technology coming first to Microsoft's rumored Surface Phone later in 2016 or early in 2017.
The most concrete advantage of 64-bit support is access to much greater amounts of memory. While a 32-bit machine can only address up to 4GB of RAM, a 64-bit machine can address up to 16 exabytes of memory. Of course, that's a theoretical limit, and today's systems made up of Windows 10 and various other hardware considerations are limited to much less RAM. Windows 10 itself can support up to 128GB on Windows 10 Home and up to 2TB on other versions.
That doesn't mean we'll see a Surface Phone running 64-bit Windows 10 Mobile shipping with 2TB of RAM, of course. However, certainly, 8GB or 16GB of RAM on a high-end phone are both physically and economically viable, and so one can imagine the things Microsoft can do with Windows 10 Mobile when they have that much memory to work with. A virtual machine-based emulator enabling Win32 app support is one thing that comes to mind.
Whatever Microsoft chooses to do with 64-bit, the writing is on the wall that they'll be implementing support for it in future versions of Windows 10 Mobile. We can't wait to see what's coming, and the Surface Phone continues to be a very exciting prospect.