For dual-monitor versions?
One avenue I looked at for a real 2560px width was that the second controller was physically independent and could have different hardware limits of the first controller by virtue of supporting DVI directly (but not being physically connected to another port).
Unfortunately other controller is logical so that was a bust.
VGA displays are something of a dying breed, and HDMI is the single likeliest interface you might find on a random newish display, so there is a market for absolute cheapest, most basic HDMI output device you can make. If you're going to build that interface, 1080p is the resolution you need to target. My point was simply that 16MB is just barely enough to build that interface, and barely enough is still enough.
^ / 1024^2[bytes/MB] = 23.73[MB]