Well, according to The Verge sources, the McLaren
is the 1020 successor.
"Evleaks first unveiled the existence of Nokia McLaren, and we understand the device will largely be seen as a Lumia 1020 successor with a similar hump in the rear casing for a powerful camera."
Microsoft bets on Kinect-like gestures for the future of Windows Phone | The Verge
Given that this is supposedly a device aimed at pulling people into the Windows Phone ecosystem, I'm not surprised Microsoft chose to combine the best of all the past and upcoming Lumia flagships into one extraordinary device. Whether that massive hump is a refined 1020 sensor or the planned dual-lens setup remains to be seen.