A correction: please note that the statue of Akatosh is widely considered the new stone for White-Gold Tower--it is not a tower itself. Important distinction.

The continent just sank so perhaps its still around, just hiding underwater somewhere. Nobody ever said that towers couldn't work underwater...

But one theory says that the continent sank because the Redguards destroyed the tower.

I've yet to see that theory. I've only heard that it was natural disaster or from the Pankratosword...

The Pankratosword is one possibility of how the Redguards could have destroyed the tower, thus sinking Yokuda.

That's what I always thought.