IESB is reporting that the Fresh Prince himself has signed on for two ID4 sequels, which would be filmed after Emmerich's next project(a William Shakespeare film, of all things) and after whichever movie Smith decides to do next(Men in Black 3?)
Both films would be shot back-to-back, possibly to begin shooting sometime in 2011.
Well, I'll try to put a positive spin on this. I knew this would eventually happen, so I'm not surprised. Will Smith is a much more discerning actor now(except for Seven Pounds!) than he was back in 1996, and his influence is far greater. If Emmerich throws out a horrendous 10,000 BC level script I'm convinced Smith will pull some magic mojo and force a rewrite or somthing. So I'll remain cautiously optimistic about this.