Meanwhile, lossless 1080p would require 20000% more space (no I didn't add too many zeros, that's 200 times more).
Of course dual link DVI et al can do more than 1080p. They are all huge. Apple's needs to support not just today's thin devices but those for the next decade (iWatch ?).
DVI, HDMI and MHL all require custom hardware in the device. As the Apple engineer said, Apple are trying to avoid this.
Avoiding custom hardware in devices just seems ridiculous - to support new standards Apple are either going to have to update their chips or update their devices, and they will have to update the cables too. There's not a saving here that isn't achieved by simply using an existing standard.
All we can guess is that Lightning can handle somewhere between 10Mbps (AirPlay over WiFi) and 2Gbps (native HDMI rates). We have absolutely no idea where in that range its actual capabilities lie.
It says nothing about Lightning maximum speed. Besides, whatever maximum speed can be measured with today hw, it doesn't mean that can be pushed tomorrow with different HW in the iDevice.
Besides, if we're talking about hypothetical future hardware, there's nothing to stop someone doing the same with micro-USB. (In fact, manufacturers already have in the form of MHL.)