If Spielberg is done Terminal, and its gone through its finishing phases, then maybe this holds water. Spielberfg takes the summer off, then kicks it up near the end to shoot in August. Harry Ford is clear. Lucas is pretty busy with Ep. III BUT he didn't actually stick to close to filming with the original. I don't think Lucas's schedule is really at stake.
The question is though, IS Terminal finished?? Only then will we know whether the POSSIBILITY is high for an August shoot.
But man I'd love to see it next year........