I have had this theory before as well. I think an earthquake may be responsible, but it may be more likely that the river to Lake Hylia simply continued to carve its way through the rock and became too deep and too wide to cross on foot or by a bridge or on foot. TP takes place more than 100 years after OoT. In OoT Gerudo valley's river had already made a huge gap and the bridge had already failed at least once. Rivers continuously eat away at the earth around them, causing it to crumble, widen, change shape, and even change direction. This can be seen easily with any major mountainous river, from Canada: The Athabasca and bow rivers are the two that stand out in my mind. It is very likely/possible that the river broke away large pieces of earth and rock and the bridge was destroyed, but the river continues to supplement the lake environment and starve the desert. In turn this created TP's map that we see today.