Kojima has been posting pictures of a very Metal Gear Solid-like quality lately and it's been getting people excited. Given Kojima Production's deep love of Big Boss in the last few years and the rapidly shrinking chronological gap between Big Boss-based games and the original Metal Gear, it was fair to think that it might have been time to look back at the first time Solid Snake joins the series.
But the greatest thing about a remake of Metal Gear is also the reason it doesn't seem likely to happen. The idea of playing through that original game with a redone story and beautiful graphics is exactly what's putting Kojima off, the amount of work to bring it in-line with the rest of the series would be too much.
On the other hand, he said that a remake of Metal Gear Solid is very much a possibility, but that he doesn't want to have to do it by himself. He's apparently always on the lookout for somebody to help control the project, although he warns that it would be on the scale of Metal Gear Solid 4 and wouldn't just be a simple task of updating the graphics.