[Windows Central Question]

Does the phone to update to Windows Phone Nokia Lumia 1520 is 10

[Pete]

Yes, the 1520 will be upgradable to Windows 10.

[Harrie-S]

Yes also the 1520 will be able to get the windows 10 update.
But it may take 6 month or more before this update is available..

[RumoredNow]

All Lumias will upgrade to 10. All other OEM's of Windows Phone will be offered 10.

Some phones will not upgrade due to OEM or Carrier constraint, even some Lumias as a carrier could drop support of that device.

Of all the current Windows Phone models, 1520 looks best poised to leverage everything 10 will debut with. Of course, Windows 10 dedicated phone hardware is expected to debut with or soon after the official public release of Windows 10 on mobile. I would expect that something better than 1520 will come along, but how long the wait is no one can say right now.