https://www.youtube.com/watch?t=203&v=0ywnDpxWuAA
^ Same processor as Lumia 920
Continuum is a rehash of features that have existed on phones for years. There is no excuse as to why Lumia 1520 and 930 would not be able to support this feature wirelessly through Miracast.
Not saying that these devices will be able to implement ALL features, however, let's break down Continuum from what we have already seen:
Lumia XXXX:
1 - Connects phone through MHL interface
2 - Target display (Monitor/TV) is a larger display, UI layouts are adjusted
3 - Apps viewed on phone maintain standard UI layouts
4 - Phone can act as a mouse/keyboard, therefore there must be a dual view implementation
5 - Phones support HID through Bluetooth USB
AT THE VERY LEAST
Lumia 1520:
1 - Connect phone through Miracast
2 - UI layouts are adjusted for target display, courtesy of Universal Apps
3 - Supports HID through Bluetooth/USB, such as Mouse, Keyboard, etc
Lumia 1520 already supports Miracast, therefore there is literally no excuse for Microsoft to not be able to implement Continuum on Televisions via single screen rendering implementation.