One thing I'd love to see is either a series of short books or a hefty 400-page hardcover giving a general take on classic settings, such as Dark Sun, Planescape, Ravenloft, Spelljammer, Birthright, and Mystara, enought to get the ball rolling but focusing mostly on the fluff. I'm thinking of Forgotten Realm's 1e level of detail, so that a lot can fit in without having to delve too deep.
No story updating, but more like a snapshot (after all, save for a few modules here and there, none of those settings undertook any considerable update like, say, FR got in 4e). Some of us have the good books of old to keep us company, but for many newcommers (or people who missed them back in the day) they are a bit of a rarity, specially in far-off markets where these things either came by in too few numbers or never showed up at all.
As for OP's question: I'd like to revisit old settings (I'm personally not at all bothered by FR being chosen as the default. I think it's the most practical and reasonable choice), but I have to say I'd be thrilled to see new stuff.