The hope for higher res TH is DisplayPort, unless I'm mistaken? I guess we'll have to see if Matrox pull some tricks for a DisplayPort TH2Go unit
´normal´ Displayport bandwidth is similar than hdmi/dvi dual link. Displayport 1.2 has double bandwidth, surely better, but still not enough for 3x2560x1600, so Displayport 1.2 only would enable 3x1920x1200 (althougth it could work at 3x25x16 at 49fps, due to maths).
Maybe hydra don´t work as we would like, but if it does, not only will allow 3x2560x1600, also it will do with more than one gpu working on it.