After looking at all the facts, I'm starting to come to the conclusion that the Metal Gear series will go the way of Resident Evil. In other words, Nintendo exclusive. More specifically, I think MGS4 will be a SK developed, Nintendo exclusive game.
If any of you remember, a while ago one French site said that a MGS remake and MGS4 would be Nintendo exclusive. I'm not sure, but I thought it was the official Nintendo of France website that said this. If anyone can confirm this, I would be very happy. Whoever said this, most people quickly dismissed the MGS4 part, largely because MGS3 hadn't even been announced then. Now it doesn't seem so absurd. Kojima said Snake Eater would be the last Metal Gear he directs. Then, Denis makes that MGS4 comment in an IGN interview. Was it more of Denis' "dramatic foreshadowing", or just a harmless comment? Plus, Denis practically confirms they're working on another game with Kojima. I suppose you could argue that it could be a non-Metal Gear game or a port of MGS2 or 3, but I bet not. Then, you have this video with Miyamoto. One thing he said jumped out at me. "You can play it till the next Metal Gear". It's very possible he could be referring to Snake Eater, but for some reason, I don't think Shiggy would be trying to get Nintendo fans to buy a competitor's system. Maybe I'm reading too much into all of this, but these sort of deals all start out small.
Anyway, my line of thinking is that if MGS4 will be a SK/Nintendo-made game, then Kojima may be passing the Metal Gear torch onto SK. Twin Snakes is just the training session.