The 'VW to F1' rumour train won't go away so let's use our crystal bollox to speculate on which other manufacturers may come into F1 in the future.
I'm going to suggest Hyundai. Despite the fact they now make pretty good cars they still have a bit of an image problem and they are now producing very good hot hatches. I could see F1 being a good move for them eventually.
Anyone else want to make a prediction?