We all know by now that there are the 3 plots of land in Falkreath, The Pale, and Hjaalmarch because these were the ones in the video. But if you on the wiki it says:
So these are potential locations which means that there can be more. Even though it says one of three plots, those were the only ones released so there can be more that we haven't been told about yet.

Then there is the achievement called Land Baron which requires you to "Buy 3 plots of land." It doesn't say to buy all 3 plots so this can suggest that there might be more plots of land to buy.

So can Bethesda be hiding some stuff from us? Because in a majority of the Holds there is more then enough room to build a house. Hell there is enough room in Whiterun Hold to make another city. So there can still be hope. That is unless Bethesda has announced that these are the only 3 plots of land and I haven't seen them say that. If so then this whole thread becomes void.

So what are your opinions on this?

I reckon there will be one more house to build in Winterhold. Like a small castle/fort in the mountings.

I certainly hope so. But the location might look too much like The Pale.