Yes, and that's already being used by the first batch of 4K monitors and is called MST. This models the monitor as 2 lower-resolution displays and drives them with two separate signals.

It has a lot of compatibility problems, and is hacky as hell. I doubt Apple would adopt this as an official/first-class solution to anything.

Exactly. They can get away with it in the iMac 5K because it's all baked into one tight enclosure.

> It has a lot of compatibility problems

Solving "compatibility problems" is what Apple do best by requiring you have an Apple Mac Pro and an Apple Cinema Display and not supporting any other configuration