Oh. So as long as you haven't visited an area, it will still load as if it was a new world?
Exactly, the "old" biomes you already explored will remain intact and the same but as new chunks load when you explore places you haven't been before, there's every chance of it creating one of the new biomes, or the "technical" transitionary ones. I have the same world I created last year and I've found a few new biomes including dark forest (or whatever it's called), savannah and ice spikes.
On another note, I had a bit of a scare last night when I created a portal near a fortress in the nether, came out about 1400 blocks away from home and used the compass to make my way towards home (actually to see if I could make some sort of road but it didn't help that the portal rezzed in a cavern under a big jungle). I then got to what should have been my original spawn point ie. the compass turned through 360 degrees as I walked around it, but it wasn't my spawn point, as I have this clearly marked out with a beacon of sorts. I then saw my original home in the distance (which had been near the spawn point) but when I got there, beyond it the chunks didn't load, for what seemed to be several hundred blocks at least, running North-South.
When I went into my old house there was just an edge then nothing, which I didn't dare try to walk off. This was also the direction of my current house, which is a few hundred blocks away, so I freaked a little thinking I might have lost it all. On top of that, I went outside and the sun came up but all the hostile mobs from the night remained frozen in position and I could walk through them, but for a few, who oddly only attacked me if I hit them (eg. a zombie trying to get through the door into my house but ignoring me)
Anyway I quit and reloaded and all was well, but if there is any game where you don't want to lose everything, and where it seems painfully easy to do so, it's this one
