There has been a lot of contention surrounding whether or not current Windows Phone 7 devices would be upgradeable to Windows Phone 8. Microsoft has finally put the rumors to rest with a resounding no, but all is not lost.
In speaking to The Verge, Greg Sullivan explains why existing hardware will not receive the upgrade:
The nature of the investment [in Windows Phone 8] is primarily in areas that are not exploitable by existing hardware.
This is understandable, since Windows Phone 8 brings support for multi-core processors and NFC, things current devices simply can’t retro-actively support. However, some changes will make the jump in a Windows Phone 7.8 update, which means the new Start Screen we previewed before will be available on existing devices.
“When you pull that Lumia out of your pocket after you’ve received that 7.8 update, it will look and feel the same as a Windows Phone 8 device.”
Of course, when pressed on which devices will be upgradeable to Windows Phone 7.8, Sullivan would not comment.