[Akhil rockstar]

Windows Mobile 10 doesn't support 64 bit. If the desktop version supports 64 bit and it's the same OS running everywhere then why there isn't support. I don't get the point. Any official Microsoft spokesperson present here in the forums?

[tRedz]

This is because 64bit can emulate arm, but arm is not powerfull enought the emulate 64bit. So the modern apps will be compatible on multible platforms, but not the desktop applications.

[RumoredNow]

By and large... Microsoft is not monitoring our Ask a Question forum. So the answer to that part of your inquiry is; sorry, but no.

There are some Microsoft employees registered as users and they peruse the Windows 10 desktop area... Have questions about the Windows 10 January Technical Preview? Join Microsoft in our forums! | Windows Central

However, there really is no need to escalate to them for an answer: tRedz has already pointed out one reason.

64 bit means more than just multi-core CPU. There is also architecture to consider: 64-bit computing - Wikipedia, the free encyclopedia

Mobile SOC (System On a Chip) design is only recently getting into this arena which PC has been using for some time. Qualcomm Snapdragon - Wikipedia, the free encyclopedia

Getting Windows 10 Mobile to the 64 bit mode would not benefit many of the existing devices. 32 bit is probably fine for mobile for the next couple of years until the SOC industry pushes out 64 bit capability to a wider proliferation level. I'm sure 64 bit Win 10 Mobile is on the roadmap, just not for the initial release.