Ok, i changed my mind and deleted the post above.

I do NOT believe that Hyrule is that big. It seems too small from what that map looks like. If it was that size, it would spell out some problems with some of the fights that we've seen in previous trailers (i.e. Link chasing after the guy riding the boar, or Link using bomb arrows to shoot down those flying monsters) The space that Link is riding in the trailers is huge, so big that even riding for a few minutes he doesn't even come upon a boundry. But from the looks of some of the pictures i've seen, the map seems to be broken up into four sectors. One of which has a kind of empty plain and the other has a giant bridge. Both spaces seem to be of same size. And i've only seen recent pictures of the bridge, and i can tell you, the field that Link battles the boar rider on must be atleast 5 to 10 times larger than that bridge.

Another thing that boggles me is that in all these trailers, we see various landscapes like Snow, rivers, forests and a fiery volcanic mine range (goron mines) Now one could assume that Hyrule field would need a lot more room for more entrances since there is all of the above locations, Toaru Village, Hyrule Castle and (only assumed) Kakariko village. (I only say Kakariko is in this game is because is exists as a precursor to Windfall Island in The Wind Waker and Twilight Princess is between Ocarina of Time and The Wind Waker.)  Anyways, i believe that this picture may only show a branch off of Hyrule Field and not the Hyrule or Hyrule Field itself.

A picture is worth a thousand words, but a trailer is plenty more.