Naturally Spawning Nether Portals

As we all know the next big update for Minecraft is the Nether Update. It was announced that we would be able to respawn in the nether and it got me thinking about what if you got trapped in the nether because you either lost or broke your portal.

I think we should have naturally spawning (uncommon/rare) portals as either a way out or a possibility to find cool new terrain in the overworld without having to mine a bunch of obsidian to keep making portals.

The portals would not follow regular portal building requirements as they could be as small as two blocks or as large as 5x5, and not just being a square or rectangle.

They can also spawn in nether caves, on the surface, or way up in the air.

I also came up with a sort of "Fractured Portal" as seen in the next picture. This would be a bit more rare.